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* Incorrect comments in commit_ts.c
@ 2018-06-22 03:45 shao bret <[email protected]>
2018-06-22 04:31 ` Re: Incorrect comments in commit_ts.c Michael Paquier <[email protected]>
0 siblings, 1 reply; 18+ messages in thread
From: shao bret @ 2018-06-22 03:45 UTC (permalink / raw)
To: [email protected] <[email protected]>
Hi,
Here is the comment for CommitTsPagePrecedes in commit_ts.c
/*
* Decide which of two CLOG page numbers is "older" for truncation purposes.
…
*/
I think there is some mistake for this comment. It should be ‘commitTS page’, not ‘CLOG page’.
Thanks,
Br.
Bret
发送自 Windows 10 版邮件<https://go.microsoft.com/fwlink/?LinkId=550986>应用
Attachments:
[application/octet-stream] 001-incorrect-comments.patch (619B, ../../KL1PR0201MB21175B59D727FDC38D731586E6750@KL1PR0201MB2117.apcprd02.prod.outlook.com/3-001-incorrect-comments.patch)
download | inline diff:
diff --git a/src/backend/access/transam/commit_ts.c b/src/backend/access/transam/commit_ts.c
index 04a15e4..8d52d45 100644
--- a/src/backend/access/transam/commit_ts.c
+++ b/src/backend/access/transam/commit_ts.c
@@ -884,7 +884,7 @@ AdvanceOldestCommitTsXid(TransactionId oldestXact)
/*
- * Decide which of two CLOG page numbers is "older" for truncation purposes.
+ * Decide which of two commitTS page numbers is "older" for truncation purposes.
*
* We need to use comparison of TransactionIds here in order to do the right
* thing with wraparound XID arithmetic. However, if we are asked about
^ permalink raw reply [nested|flat] 18+ messages in thread
* Re: Incorrect comments in commit_ts.c
2018-06-22 03:45 Incorrect comments in commit_ts.c shao bret <[email protected]>
@ 2018-06-22 04:31 ` Michael Paquier <[email protected]>
2018-06-22 07:34 ` =?gb2312?B?tPC4tDogSW5jb3JyZWN0IGNvbW1lbnRzIGluIGNvbW1pdF90cy5j?= shao bret <[email protected]>
0 siblings, 1 reply; 18+ messages in thread
From: Michael Paquier @ 2018-06-22 04:31 UTC (permalink / raw)
To: shao bret <[email protected]>; +Cc: [email protected] <[email protected]>
On Fri, Jun 22, 2018 at 03:45:01AM +0000, shao bret wrote:
> I think there is some mistake for this comment. It should be
> ‘commitTS page’, not ‘CLOG page’.
You are right, so pushed.
--
Michael
Attachments:
[application/pgp-signature] signature.asc (833B, ../../[email protected]/2-signature.asc)
download
^ permalink raw reply [nested|flat] 18+ messages in thread
* =?gb2312?B?tPC4tDogSW5jb3JyZWN0IGNvbW1lbnRzIGluIGNvbW1pdF90cy5j?=
2018-06-22 03:45 Incorrect comments in commit_ts.c shao bret <[email protected]>
2018-06-22 04:31 ` Re: Incorrect comments in commit_ts.c Michael Paquier <[email protected]>
@ 2018-06-22 07:34 ` shao bret <[email protected]>
0 siblings, 0 replies; 18+ messages in thread
From: shao bret @ 2018-06-22 07:34 UTC (permalink / raw)
To: Michael Paquier <[email protected]>; +Cc: [email protected] <[email protected]>
Thanks, I have seen the code change.
Br.
Bret.
HighGo Software
Website：http://www.highgo.com/?l=en
发送自 Windows 10 版邮件<https://go.microsoft.com/fwlink/?LinkId=550986>应用
发件人: Michael Paquier<mailto:[email protected]>
发送时间: 2018年6月22日 12:32
收件人: shao bret<mailto:[email protected]>
抄送: [email protected]<mailto:[email protected]>
主题: Re: Incorrect comments in commit_ts.c
On Fri, Jun 22, 2018 at 03:45:01AM +0000, shao bret wrote:
> I think there is some mistake for this comment. It should be
> ‘commitTS page’, not ‘CLOG page’.
You are right, so pushed.
--
Michael
^ permalink raw reply [nested|flat] 18+ messages in thread
* [PATCH v3 12/17] Merge prune and freeze records
@ 2024-01-07 22:55 Melanie Plageman <[email protected]>
0 siblings, 0 replies; 18+ messages in thread
From: Melanie Plageman @ 2024-01-07 22:55 UTC (permalink / raw)
When there are both tuples to prune and freeze on a page, emit a single,
combined prune record containing the offsets for pruning and the freeze
plans and offsets for freezing. This will reduce the number of WAL
records emitted.
---
src/backend/access/heap/heapam.c | 42 ++++++++++++--
src/backend/access/heap/pruneheap.c | 85 +++++++++++++----------------
src/include/access/heapam_xlog.h | 20 +++++--
3 files changed, 90 insertions(+), 57 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index a3691584c55..a8f35eba3c9 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8803,24 +8803,28 @@ heap_xlog_prune(XLogReaderState *record)
if (action == BLK_NEEDS_REDO)
{
Page page = (Page) BufferGetPage(buffer);
- OffsetNumber *end;
OffsetNumber *redirected;
OffsetNumber *nowdead;
OffsetNumber *nowunused;
int nredirected;
int ndead;
int nunused;
+ int nplans;
Size datalen;
+ xl_heap_freeze_plan *plans;
+ OffsetNumber *frz_offsets;
+ int curoff = 0;
- redirected = (OffsetNumber *) XLogRecGetBlockData(record, 0, &datalen);
-
+ nplans = xlrec->nplans;
nredirected = xlrec->nredirected;
ndead = xlrec->ndead;
- end = (OffsetNumber *) ((char *) redirected + datalen);
+ nunused = xlrec->nunused;
+
+ plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, &datalen);
+ redirected = (OffsetNumber *) &plans[nplans];
nowdead = redirected + (nredirected * 2);
nowunused = nowdead + ndead;
- nunused = (end - nowunused);
- Assert(nunused >= 0);
+ frz_offsets = nowunused + nunused;
/* Update all line pointers per the record, and repair fragmentation */
heap_page_prune_execute(buffer,
@@ -8828,6 +8832,32 @@ heap_xlog_prune(XLogReaderState *record)
nowdead, ndead,
nowunused, nunused);
+ for (int p = 0; p < nplans; p++)
+ {
+ HeapTupleFreeze frz;
+
+ /*
+ * Convert freeze plan representation from WAL record into
+ * per-tuple format used by heap_execute_freeze_tuple
+ */
+ frz.xmax = plans[p].xmax;
+ frz.t_infomask2 = plans[p].t_infomask2;
+ frz.t_infomask = plans[p].t_infomask;
+ frz.frzflags = plans[p].frzflags;
+ frz.offset = InvalidOffsetNumber; /* unused, but be tidy */
+
+ for (int i = 0; i < plans[p].ntuples; i++)
+ {
+ OffsetNumber offset = frz_offsets[curoff++];
+ ItemId lp;
+ HeapTupleHeader tuple;
+
+ lp = PageGetItemId(page, offset);
+ tuple = (HeapTupleHeader) PageGetItem(page, lp);
+ heap_execute_freeze_tuple(tuple, &frz);
+ }
+ }
+
/*
* Note: we don't worry about updating the page's prunability hints.
* At worst this will cause an extra prune cycle to occur soon.
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index d77270ad0d6..994cf75c54e 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -619,6 +619,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
*/
PageClearFull(page);
+ if (do_freeze)
+ heap_freeze_prepared_tuples(buffer, frozen, presult->nfrozen);
+
MarkBufferDirty(buffer);
/*
@@ -629,10 +632,37 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
xl_heap_prune xlrec;
XLogRecPtr recptr;
+ xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
+ OffsetNumber offsets[MaxHeapTuplesPerPage];
+
xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
xlrec.nredirected = prstate.nredirected;
xlrec.ndead = prstate.ndead;
+ xlrec.nunused = prstate.nunused;
+ xlrec.nplans = 0;
+
+ /*
+ * The snapshotConflictHorizon for the whole record should be the most
+ * conservative of all the horizons calculated for any of the possible
+ * modifications. If this record will prune tuples, any transactions
+ * on the standby older than the youngest xmax of the most recently
+ * removed tuple this record will prune will conflict. If this record
+ * will freeze tuples, any transactions on the standby with xids older
+ * than the youngest tuple this record will freeze will conflict.
+ */
+ if (do_freeze)
+ xlrec.snapshotConflictHorizon = Max(prstate.snapshotConflictHorizon,
+ frz_conflict_horizon);
+ else
+ xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
+
+ /*
+ * Prepare deduplicated representation for use in WAL record
+ * Destructively sorts tuples array in-place.
+ */
+ if (do_freeze)
+ xlrec.nplans = heap_log_freeze_plan(frozen,
+ presult->nfrozen, plans, offsets);
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapPrune);
@@ -644,6 +674,10 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* pretend that they are. When XLogInsert stores the whole buffer,
* the offset arrays need not be stored too.
*/
+ if (xlrec.nplans > 0)
+ XLogRegisterBufData(0, (char *) plans,
+ xlrec.nplans * sizeof(xl_heap_freeze_plan));
+
if (prstate.nredirected > 0)
XLogRegisterBufData(0, (char *) prstate.redirected,
prstate.nredirected *
@@ -657,56 +691,13 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
XLogRegisterBufData(0, (char *) prstate.nowunused,
prstate.nunused * sizeof(OffsetNumber));
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
-
- PageSetLSN(BufferGetPage(buffer), recptr);
- }
-
- if (do_freeze)
- {
- Assert(presult->nfrozen > 0);
-
- heap_freeze_prepared_tuples(buffer, frozen, presult->nfrozen);
-
- MarkBufferDirty(buffer);
-
- /* Now WAL-log freezing if necessary */
- if (RelationNeedsWAL(relation))
- {
- xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
- OffsetNumber offsets[MaxHeapTuplesPerPage];
- int nplans;
- xl_heap_freeze_page xlrec;
- XLogRecPtr recptr;
-
- /*
- * Prepare deduplicated representation for use in WAL record
- * Destructively sorts tuples array in-place.
- */
- nplans = heap_log_freeze_plan(frozen, presult->nfrozen, plans, offsets);
-
- xlrec.snapshotConflictHorizon = frz_conflict_horizon;
- xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.nplans = nplans;
-
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, SizeOfHeapFreezePage);
-
- /*
- * The freeze plan array and offset array are not actually in the
- * buffer, but pretend that they are. When XLogInsert stores the
- * whole buffer, the arrays need not be stored too.
- */
- XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
- XLogRegisterBufData(0, (char *) plans,
- nplans * sizeof(xl_heap_freeze_plan));
+ if (xlrec.nplans > 0)
XLogRegisterBufData(0, (char *) offsets,
presult->nfrozen * sizeof(OffsetNumber));
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_FREEZE_PAGE);
+ recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
- PageSetLSN(page, recptr);
- }
+ PageSetLSN(BufferGetPage(buffer), recptr);
}
END_CRIT_SECTION();
diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h
index 6488dad5e64..22f236bb52a 100644
--- a/src/include/access/heapam_xlog.h
+++ b/src/include/access/heapam_xlog.h
@@ -231,23 +231,35 @@ typedef struct xl_heap_update
* during opportunistic pruning)
*
* The array of OffsetNumbers following the fixed part of the record contains:
+ * * for each freeze plan: the freeze plan
* * for each redirected item: the item offset, then the offset redirected to
* * for each now-dead item: the item offset
* * for each now-unused item: the item offset
- * The total number of OffsetNumbers is therefore 2*nredirected+ndead+nunused.
- * Note that nunused is not explicitly stored, but may be found by reference
- * to the total record length.
+ * * for each tuple frozen by the freeze plans: the offset of the item corresponding to that tuple
+ * The total number of OffsetNumbers is therefore
+ * (2*nredirected) + ndead + nunused + (sum[plan.ntuples for plan in plans])
*
* Acquires a full cleanup lock.
*/
typedef struct xl_heap_prune
{
TransactionId snapshotConflictHorizon;
+ uint16 nplans;
uint16 nredirected;
uint16 ndead;
+ uint16 nunused;
bool isCatalogRel; /* to handle recovery conflict during logical
* decoding on standby */
- /* OFFSET NUMBERS are in the block reference 0 */
+ /*
+ * OFFSET NUMBERS and freeze plans are in the block reference 0 in the
+ * following order:
+ *
+ * * xl_heap_freeze_plan plans[nplans];
+ * * OffsetNumber redirected[2 * nredirected];
+ * * OffsetNumber nowdead[ndead];
+ * * OffsetNumber nowunused[nunused];
+ * * OffsetNumber frz_offsets[...];
+ */
} xl_heap_prune;
#define SizeOfHeapPrune (offsetof(xl_heap_prune, isCatalogRel) + sizeof(bool))
--
2.40.1
--racicctn4wry6xe5
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v3-0013-Set-hastup-in-heap_page_prune.patch"
^ permalink raw reply [nested|flat] 18+ messages in thread
* [PATCH v4 13/19] Merge prune and freeze records
@ 2024-01-07 22:55 Melanie Plageman <[email protected]>
0 siblings, 0 replies; 18+ messages in thread
From: Melanie Plageman @ 2024-01-07 22:55 UTC (permalink / raw)
Eliminate xl_heap_freeze and XLOG_HEAP2_FREEZE record. When vacuum
freezes tuples, the information needed to replay those changes is
now recorded in the xl_heap_prune record.
When both pruning and freezing is done, this means a single, combined
WAL record is emitted for both operations. This will reduce the number
of WAL records emitted.
When there are only tuples to freeze present, we can avoid taking a full
cleanup lock when replaying the record.
The XLOG_HEAP2_PRUNE record is now bigger than it was previously and
bigger than the XLOG_HEAP2_FREEZE record. A future commit will
streamline the record.
---
src/backend/access/heap/heapam.c | 146 ++++------
src/backend/access/heap/pruneheap.c | 326 ++++++++++++-----------
src/backend/access/rmgrdesc/heapdesc.c | 95 ++++---
src/backend/replication/logical/decode.c | 1 -
src/include/access/heapam_xlog.h | 97 ++++---
5 files changed, 318 insertions(+), 347 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index e47b56e7856..532868039d5 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8706,8 +8706,6 @@ ExtractReplicaIdentity(Relation relation, HeapTuple tp, bool key_required,
/*
* Handles XLOG_HEAP2_PRUNE record type.
- *
- * Acquires a full cleanup lock.
*/
static void
heap_xlog_prune(XLogReaderState *record)
@@ -8718,12 +8716,22 @@ heap_xlog_prune(XLogReaderState *record)
RelFileLocator rlocator;
BlockNumber blkno;
XLogRedoAction action;
+ bool get_cleanup_lock;
XLogRecGetBlockTag(record, 0, &rlocator, NULL, &blkno);
/*
- * We're about to remove tuples. In Hot Standby mode, ensure that there's
- * no queries running for which the removed tuples are still visible.
+ * If there are dead, redirected, or unused items set unused by
+ * heap_page_prune_and_freeze(), heap_page_prune_execute() will call
+ * PageRepairFragementation() which expects a full cleanup lock.
+ */
+ get_cleanup_lock = xlrec->nredirected > 0 ||
+ xlrec->ndead > 0 || xlrec->nunused > 0;
+
+ /*
+ * We are either about to remove tuples or freeze them. In Hot Standby
+ * mode, ensure that there's no queries running for which any removed
+ * tuples are still visible or which consider the frozen xids as running.
*/
if (InHotStandby)
ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
@@ -8731,38 +8739,69 @@ heap_xlog_prune(XLogReaderState *record)
rlocator);
/*
- * If we have a full-page image, restore it (using a cleanup lock) and
- * we're done.
+ * If we have a full-page image, restore it and we're done.
*/
- action = XLogReadBufferForRedoExtended(record, 0, RBM_NORMAL, true,
- &buffer);
+ action = XLogReadBufferForRedoExtended(record, 0, RBM_NORMAL,
+ get_cleanup_lock, &buffer);
+
if (action == BLK_NEEDS_REDO)
{
Page page = (Page) BufferGetPage(buffer);
- OffsetNumber *end;
OffsetNumber *redirected;
OffsetNumber *nowdead;
OffsetNumber *nowunused;
int nredirected;
int ndead;
int nunused;
+ int nplans;
Size datalen;
+ xl_heap_freeze_plan *plans;
+ OffsetNumber *frz_offsets;
+ int curoff = 0;
- redirected = (OffsetNumber *) XLogRecGetBlockData(record, 0, &datalen);
-
+ nplans = xlrec->nplans;
nredirected = xlrec->nredirected;
ndead = xlrec->ndead;
- end = (OffsetNumber *) ((char *) redirected + datalen);
+ nunused = xlrec->nunused;
+
+ plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, &datalen);
+ redirected = (OffsetNumber *) &plans[nplans];
nowdead = redirected + (nredirected * 2);
nowunused = nowdead + ndead;
- nunused = (end - nowunused);
- Assert(nunused >= 0);
+ frz_offsets = nowunused + nunused;
/* Update all line pointers per the record, and repair fragmentation */
- heap_page_prune_execute(buffer,
- redirected, nredirected,
- nowdead, ndead,
- nowunused, nunused);
+ if (nredirected > 0 || ndead > 0 || nunused > 0)
+ heap_page_prune_execute(buffer,
+ redirected, nredirected,
+ nowdead, ndead,
+ nowunused, nunused);
+
+ for (int p = 0; p < nplans; p++)
+ {
+ HeapTupleFreeze frz;
+
+ /*
+ * Convert freeze plan representation from WAL record into
+ * per-tuple format used by heap_execute_freeze_tuple
+ */
+ frz.xmax = plans[p].xmax;
+ frz.t_infomask2 = plans[p].t_infomask2;
+ frz.t_infomask = plans[p].t_infomask;
+ frz.frzflags = plans[p].frzflags;
+ frz.offset = InvalidOffsetNumber; /* unused, but be tidy */
+
+ for (int i = 0; i < plans[p].ntuples; i++)
+ {
+ OffsetNumber offset = frz_offsets[curoff++];
+ ItemId lp;
+ HeapTupleHeader tuple;
+
+ lp = PageGetItemId(page, offset);
+ tuple = (HeapTupleHeader) PageGetItem(page, lp);
+ heap_execute_freeze_tuple(tuple, &frz);
+ }
+ }
/*
* Note: we don't worry about updating the page's prunability hints.
@@ -9001,74 +9040,6 @@ heap_xlog_visible(XLogReaderState *record)
UnlockReleaseBuffer(vmbuffer);
}
-/*
- * Replay XLOG_HEAP2_FREEZE_PAGE records
- */
-static void
-heap_xlog_freeze_page(XLogReaderState *record)
-{
- XLogRecPtr lsn = record->EndRecPtr;
- xl_heap_freeze_page *xlrec = (xl_heap_freeze_page *) XLogRecGetData(record);
- Buffer buffer;
-
- /*
- * In Hot Standby mode, ensure that there's no queries running which still
- * consider the frozen xids as running.
- */
- if (InHotStandby)
- {
- RelFileLocator rlocator;
-
- XLogRecGetBlockTag(record, 0, &rlocator, NULL, NULL);
- ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
- xlrec->isCatalogRel,
- rlocator);
- }
-
- if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
- {
- Page page = BufferGetPage(buffer);
- xl_heap_freeze_plan *plans;
- OffsetNumber *offsets;
- int curoff = 0;
-
- plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, NULL);
- offsets = (OffsetNumber *) ((char *) plans +
- (xlrec->nplans *
- sizeof(xl_heap_freeze_plan)));
- for (int p = 0; p < xlrec->nplans; p++)
- {
- HeapTupleFreeze frz;
-
- /*
- * Convert freeze plan representation from WAL record into
- * per-tuple format used by heap_execute_freeze_tuple
- */
- frz.xmax = plans[p].xmax;
- frz.t_infomask2 = plans[p].t_infomask2;
- frz.t_infomask = plans[p].t_infomask;
- frz.frzflags = plans[p].frzflags;
- frz.offset = InvalidOffsetNumber; /* unused, but be tidy */
-
- for (int i = 0; i < plans[p].ntuples; i++)
- {
- OffsetNumber offset = offsets[curoff++];
- ItemId lp;
- HeapTupleHeader tuple;
-
- lp = PageGetItemId(page, offset);
- tuple = (HeapTupleHeader) PageGetItem(page, lp);
- heap_execute_freeze_tuple(tuple, &frz);
- }
- }
-
- PageSetLSN(page, lsn);
- MarkBufferDirty(buffer);
- }
- if (BufferIsValid(buffer))
- UnlockReleaseBuffer(buffer);
-}
-
/*
* Given an "infobits" field from an XLog record, set the correct bits in the
* given infomask and infomask2 for the tuple touched by the record.
@@ -9975,9 +9946,6 @@ heap2_redo(XLogReaderState *record)
case XLOG_HEAP2_VACUUM:
heap_xlog_vacuum(record);
break;
- case XLOG_HEAP2_FREEZE_PAGE:
- heap_xlog_freeze_page(record);
- break;
case XLOG_HEAP2_VISIBLE:
heap_xlog_visible(record);
break;
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index 7bd479cfd4e..19b50931b90 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -79,6 +79,9 @@ static void heap_prune_record_dead_or_unused(PruneState *prstate, OffsetNumber o
static void heap_prune_record_unused(PruneState *prstate, OffsetNumber offnum);
static void page_verify_redirects(Page page);
+static void log_heap_prune_and_freeze(Relation relation, Buffer buffer,
+ PruneState *prstate, PruneFreezeResult *presult);
+
/*
* Optionally prune and repair fragmentation in the specified page.
@@ -247,9 +250,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
HeapTupleData tup;
bool do_freeze;
bool do_prune;
+ bool do_hint;
bool whole_page_freezable;
bool hint_bit_fpi;
- bool prune_fpi = false;
int64 fpi_before = pgWalUsage.wal_fpi;
/*
@@ -445,10 +448,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
/*
* If checksums are enabled, heap_prune_satisfies_vacuum() may have caused
- * an FPI to be emitted. Then reset fpi_before for no prune case.
+ * an FPI to be emitted.
*/
hint_bit_fpi = fpi_before != pgWalUsage.wal_fpi;
- fpi_before = pgWalUsage.wal_fpi;
/*
* For vacuum, if the whole page will become frozen, we consider
@@ -498,14 +500,18 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
prstate.ndead > 0 ||
prstate.nunused > 0;
+ /* Record number of newly-set-LP_DEAD items for caller */
+ presult->nnewlpdead = prstate.ndead;
+
/*
- * Only incur overhead of checking if we will do an FPI if we might use
- * the information.
+ * Even if we don't prune anything, if we found a new value for the
+ * pd_prune_xid field or the page was marked full, we will update the hint
+ * bit.
*/
- if (do_prune && pagefrz)
- prune_fpi = XLogCheckBufferNeedsBackup(buffer);
+ do_hint = ((PageHeader) page)->pd_prune_xid != prstate.new_prune_xid ||
+ PageIsFull(page);
- /* Is the whole page freezable? And is there something to freeze */
+ /* Is the whole page freezable? And is there something to freeze? */
whole_page_freezable = presult->all_visible_except_removable &&
presult->all_frozen;
@@ -520,43 +526,51 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* opportunistic freeze heuristic must be improved; however, for now, try
* to approximate it.
*/
- do_freeze = pagefrz &&
- (pagefrz->freeze_required ||
- (whole_page_freezable && presult->nfrozen > 0 && (prune_fpi || hint_bit_fpi)));
+ do_freeze = false;
+ if (pagefrz)
+ {
+ if (pagefrz->freeze_required)
+ do_freeze = true;
+ else if (whole_page_freezable && presult->nfrozen > 0)
+ {
+ /*
+ * Freezing would make the page all-frozen. In this case, we will
+ * freeze if we have already emitted an FPI or will do so anyway.
+ * Be sure only to incur the overhead of checking if we will do an
+ * FPI if we may use that information.
+ */
+ if (hint_bit_fpi ||
+ ((do_prune || do_hint) && XLogCheckBufferNeedsBackup(buffer)))
+ {
+ do_freeze = true;
+ }
+ }
+ }
+ /*
+ * Validate the tuples we are considering freezing. We do this even if
+ * pruning and hint bit setting have not emitted an FPI so far because we
+ * still may emit an FPI while setting the page hint bit later. But we
+ * want to avoid doing the pre-freeze checks in a critical section.
+ */
if (do_freeze)
- {
heap_pre_freeze_checks(buffer, prstate.frozen, presult->nfrozen);
+ if (!do_freeze && (!pagefrz || !presult->all_frozen || presult->nfrozen > 0))
+ {
/*
- * We can use frz_conflict_horizon as our cutoff for conflicts when
- * the whole page is eligible to become all-frozen in the VM once
- * we're done with it. Otherwise we generate a conservative cutoff by
- * stepping back from OldestXmin.
+ * If we will neither freeze tuples on the page nor set the page all
+ * frozen in the visibility map, the page is not all-frozen and there
+ * will be no newly frozen tuples.
*/
- if (!(presult->all_visible_except_removable && presult->all_frozen))
- {
- /* Avoids false conflicts when hot_standby_feedback in use */
- presult->frz_conflict_horizon = pagefrz->cutoffs->OldestXmin;
- TransactionIdRetreat(presult->frz_conflict_horizon);
- }
+ presult->all_frozen = false;
+ presult->nfrozen = 0; /* avoid miscounts in instrumentation */
}
- /* Any error while applying the changes is critical */
START_CRIT_SECTION();
- /* Have we found any prunable items? */
- if (do_prune)
+ if (do_hint)
{
- /*
- * Apply the planned item changes, then repair page fragmentation, and
- * update the page's hint bit about whether it has free line pointers.
- */
- heap_page_prune_execute(buffer,
- prstate.redirected, prstate.nredirected,
- prstate.nowdead, prstate.ndead,
- prstate.nowunused, prstate.nunused);
-
/*
* Update the page's pd_prune_xid field to either zero, or the lowest
* XID of any soon-prunable tuple.
@@ -564,163 +578,159 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid;
/*
- * Also clear the "page is full" flag, since there's no point in
- * repeating the prune/defrag process until something else happens to
- * the page.
+ * Clear the "page is full" flag if it is set since there's no point
+ * in repeating the prune/defrag process until something else happens
+ * to the page.
*/
PageClearFull(page);
- MarkBufferDirty(buffer);
+ /*
+ * We only needed to update pd_prune_xid and clear the page-is-full
+ * hint bit, this is a non-WAL-logged hint. If we will also freeze or
+ * prune the page, we will mark the buffer dirty below.
+ */
+ if (!do_freeze && !do_prune)
+ MarkBufferDirtyHint(buffer, true);
+ }
+ if (do_prune || do_freeze)
+ {
/*
- * Emit a WAL XLOG_HEAP2_PRUNE record showing what we did
+ * Apply the planned item changes, then repair page fragmentation, and
+ * update the page's hint bit about whether it has free line pointers.
*/
- if (RelationNeedsWAL(relation))
+ if (do_prune)
{
- xl_heap_prune xlrec;
- XLogRecPtr recptr;
-
- xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
- xlrec.nredirected = prstate.nredirected;
- xlrec.ndead = prstate.ndead;
-
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, SizeOfHeapPrune);
-
- XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
+ heap_page_prune_execute(buffer,
+ prstate.redirected, prstate.nredirected,
+ prstate.nowdead, prstate.ndead,
+ prstate.nowunused, prstate.nunused);
+ }
+ if (do_freeze)
+ {
/*
- * The OffsetNumber arrays are not actually in the buffer, but we
- * pretend that they are. When XLogInsert stores the whole
- * buffer, the offset arrays need not be stored too.
+ * We can use frz_conflict_horizon as our cutoff for conflicts
+ * when the whole page is eligible to become all-frozen in the VM
+ * once we're done with it. Otherwise we generate a conservative
+ * cutoff by stepping back from OldestXmin. This avoids false
+ * conflicts when hot_standby_feedback is in use.
*/
- if (prstate.nredirected > 0)
- XLogRegisterBufData(0, (char *) prstate.redirected,
- prstate.nredirected *
- sizeof(OffsetNumber) * 2);
-
- if (prstate.ndead > 0)
- XLogRegisterBufData(0, (char *) prstate.nowdead,
- prstate.ndead * sizeof(OffsetNumber));
-
- if (prstate.nunused > 0)
- XLogRegisterBufData(0, (char *) prstate.nowunused,
- prstate.nunused * sizeof(OffsetNumber));
+ if (!(presult->all_visible_except_removable && presult->all_frozen))
+ {
+ presult->frz_conflict_horizon = pagefrz->cutoffs->OldestXmin;
+ TransactionIdRetreat(presult->frz_conflict_horizon);
+ }
+ heap_freeze_prepared_tuples(buffer, prstate.frozen, presult->nfrozen);
+ }
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
+ MarkBufferDirty(buffer);
- PageSetLSN(BufferGetPage(buffer), recptr);
- }
- }
- else
- {
/*
- * If we didn't prune anything, but have found a new value for the
- * pd_prune_xid field, update it and mark the buffer dirty. This is
- * treated as a non-WAL-logged hint.
- *
- * Also clear the "page is full" flag if it is set, since there's no
- * point in repeating the prune/defrag process until something else
- * happens to the page.
+ * Emit a WAL XLOG_HEAP2_PRUNE record showing what we did
*/
- if (((PageHeader) page)->pd_prune_xid != prstate.new_prune_xid ||
- PageIsFull(page))
- {
- ((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid;
- PageClearFull(page);
- MarkBufferDirtyHint(buffer, true);
- }
+ if (RelationNeedsWAL(relation))
+ log_heap_prune_and_freeze(relation, buffer, &prstate, presult);
}
END_CRIT_SECTION();
- /* Record number of newly-set-LP_DEAD items for caller */
- presult->nnewlpdead = prstate.ndead;
-
- if (do_freeze)
+ /*
+ * If we froze tuples on the page, the caller can advance relfrozenxid and
+ * relminmxid to the values in pagefrz->FreezePageRelfrozenXid and
+ * pagefrz->FreezePageRelminMxid. Otherwise, it is only safe to advance to
+ * the values in pagefrz->NoFreezePage[RelfrozenXid|RelminMxid]
+ */
+ if (pagefrz)
{
- START_CRIT_SECTION();
+ if (presult->nfrozen > 0)
+ {
+ presult->new_relfrozenxid = pagefrz->FreezePageRelfrozenXid;
+ presult->new_relminmxid = pagefrz->FreezePageRelminMxid;
+ }
+ else
+ {
+ presult->new_relfrozenxid = pagefrz->NoFreezePageRelfrozenXid;
+ presult->new_relminmxid = pagefrz->NoFreezePageRelminMxid;
+ }
+ }
+}
- Assert(presult->nfrozen > 0);
- heap_freeze_prepared_tuples(buffer, prstate.frozen, presult->nfrozen);
+static void
+log_heap_prune_and_freeze(Relation relation, Buffer buffer,
+ PruneState *prstate, PruneFreezeResult *presult)
+{
+ xl_heap_prune xlrec;
+ XLogRecPtr recptr;
- MarkBufferDirty(buffer);
+ xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
+ OffsetNumber offsets[MaxHeapTuplesPerPage];
+ bool do_freeze = presult->nfrozen > 0;
- /* Now WAL-log freezing if necessary */
- if (RelationNeedsWAL(relation))
- {
- xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
- OffsetNumber offsets[MaxHeapTuplesPerPage];
- int nplans;
- xl_heap_freeze_page xlrec;
- XLogRecPtr recptr;
+ xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
+ xlrec.nredirected = prstate->nredirected;
+ xlrec.ndead = prstate->ndead;
+ xlrec.nunused = prstate->nunused;
+ xlrec.nplans = 0;
- /*
- * Prepare deduplicated representation for use in WAL record
- * Destructively sorts tuples array in-place.
- */
- nplans = heap_log_freeze_plan(prstate.frozen, presult->nfrozen, plans, offsets);
+ /*
+ * The snapshotConflictHorizon for the whole record should be the most
+ * conservative of all the horizons calculated for any of the possible
+ * modifications. If this record will prune tuples, any transactions on
+ * the standby older than the youngest xmax of the most recently removed
+ * tuple this record will prune will conflict. If this record will freeze
+ * tuples, any transactions on the standby with xids older than the
+ * youngest tuple this record will freeze will conflict.
+ */
+ if (do_freeze)
+ xlrec.snapshotConflictHorizon = Max(prstate->snapshotConflictHorizon,
+ presult->frz_conflict_horizon);
+ else
+ xlrec.snapshotConflictHorizon = prstate->snapshotConflictHorizon;
- xlrec.snapshotConflictHorizon = presult->frz_conflict_horizon;
- xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.nplans = nplans;
+ /*
+ * Prepare deduplicated representation for use in WAL record Destructively
+ * sorts tuples array in-place.
+ */
+ if (do_freeze)
+ xlrec.nplans = heap_log_freeze_plan(prstate->frozen,
+ presult->nfrozen, plans, offsets);
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, SizeOfHeapFreezePage);
+ XLogBeginInsert();
+ XLogRegisterData((char *) &xlrec, SizeOfHeapPrune);
- /*
- * The freeze plan array and offset array are not actually in the
- * buffer, but pretend that they are. When XLogInsert stores the
- * whole buffer, the arrays need not be stored too.
- */
- XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
- XLogRegisterBufData(0, (char *) plans,
- nplans * sizeof(xl_heap_freeze_plan));
- XLogRegisterBufData(0, (char *) offsets,
- presult->nfrozen * sizeof(OffsetNumber));
+ XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_FREEZE_PAGE);
+ /*
+ * The OffsetNumber arrays are not actually in the buffer, but we pretend
+ * that they are. When XLogInsert stores the whole buffer, the offset
+ * arrays need not be stored too.
+ */
+ if (xlrec.nplans > 0)
+ XLogRegisterBufData(0, (char *) plans,
+ xlrec.nplans * sizeof(xl_heap_freeze_plan));
- PageSetLSN(page, recptr);
- }
+ if (prstate->nredirected > 0)
+ XLogRegisterBufData(0, (char *) prstate->redirected,
+ prstate->nredirected *
+ sizeof(OffsetNumber) * 2);
- END_CRIT_SECTION();
- }
- else if (!pagefrz || !presult->all_frozen || presult->nfrozen > 0)
- {
- /*
- * If we will neither freeze tuples on the page nor set the page all
- * frozen in the visibility map, the page is not all frozen and there
- * will be no newly frozen tuples.
- */
- presult->all_frozen = false;
- presult->nfrozen = 0; /* avoid miscounts in instrumentation */
- }
+ if (prstate->ndead > 0)
+ XLogRegisterBufData(0, (char *) prstate->nowdead,
+ prstate->ndead * sizeof(OffsetNumber));
- /* Caller won't update new_relfrozenxid and new_relminmxid */
- if (!pagefrz)
- return;
+ if (prstate->nunused > 0)
+ XLogRegisterBufData(0, (char *) prstate->nowunused,
+ prstate->nunused * sizeof(OffsetNumber));
+ if (xlrec.nplans > 0)
+ XLogRegisterBufData(0, (char *) offsets,
+ presult->nfrozen * sizeof(OffsetNumber));
- /*
- * If we will freeze tuples on the page or, even if we don't freeze tuples
- * on the page, if we will set the page all-frozen in the visibility map,
- * we can advance relfrozenxid and relminmxid to the values in
- * pagefrz->FreezePageRelfrozenXid and pagefrz->FreezePageRelminMxid.
- */
- if (presult->all_frozen || presult->nfrozen > 0)
- {
- presult->new_relfrozenxid = pagefrz->FreezePageRelfrozenXid;
- presult->new_relminmxid = pagefrz->FreezePageRelminMxid;
- }
- else
- {
- presult->new_relfrozenxid = pagefrz->NoFreezePageRelfrozenXid;
- presult->new_relminmxid = pagefrz->NoFreezePageRelminMxid;
- }
-}
+ recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
+ PageSetLSN(BufferGetPage(buffer), recptr);
+}
/*
* Perform visibility checks for heap pruning.
diff --git a/src/backend/access/rmgrdesc/heapdesc.c b/src/backend/access/rmgrdesc/heapdesc.c
index 36a3d83c8c2..9f0a0341d40 100644
--- a/src/backend/access/rmgrdesc/heapdesc.c
+++ b/src/backend/access/rmgrdesc/heapdesc.c
@@ -179,43 +179,67 @@ heap2_desc(StringInfo buf, XLogReaderState *record)
{
xl_heap_prune *xlrec = (xl_heap_prune *) rec;
- appendStringInfo(buf, "snapshotConflictHorizon: %u, nredirected: %u, ndead: %u, isCatalogRel: %c",
+ appendStringInfo(buf, "snapshotConflictHorizon: %u, isCatalogRel: %c",
xlrec->snapshotConflictHorizon,
- xlrec->nredirected,
- xlrec->ndead,
xlrec->isCatalogRel ? 'T' : 'F');
if (XLogRecHasBlockData(record, 0))
{
- OffsetNumber *end;
OffsetNumber *redirected;
OffsetNumber *nowdead;
OffsetNumber *nowunused;
int nredirected;
+ int ndead;
int nunused;
+ int nplans;
Size datalen;
+ xl_heap_freeze_plan *plans;
+ OffsetNumber *frz_offsets;
- redirected = (OffsetNumber *) XLogRecGetBlockData(record, 0,
- &datalen);
-
+ nplans = xlrec->nplans;
nredirected = xlrec->nredirected;
- end = (OffsetNumber *) ((char *) redirected + datalen);
- nowdead = redirected + (nredirected * 2);
- nowunused = nowdead + xlrec->ndead;
- nunused = (end - nowunused);
- Assert(nunused >= 0);
+ ndead = xlrec->ndead;
+ nunused = xlrec->nunused;
- appendStringInfo(buf, ", nunused: %d", nunused);
-
- appendStringInfoString(buf, ", redirected:");
- array_desc(buf, redirected, sizeof(OffsetNumber) * 2,
- nredirected, &redirect_elem_desc, NULL);
- appendStringInfoString(buf, ", dead:");
- array_desc(buf, nowdead, sizeof(OffsetNumber), xlrec->ndead,
- &offset_elem_desc, NULL);
- appendStringInfoString(buf, ", unused:");
- array_desc(buf, nowunused, sizeof(OffsetNumber), nunused,
- &offset_elem_desc, NULL);
+ plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, &datalen);
+ redirected = (OffsetNumber *) &plans[nplans];
+ nowdead = redirected + (nredirected * 2);
+ nowunused = nowdead + ndead;
+ frz_offsets = nowunused + nunused;
+
+ appendStringInfo(buf, ", nredirected: %u, ndead: %u, nunused: %u, nplans: %u,",
+ nredirected,
+ ndead,
+ nunused,
+ nplans);
+
+ if (nredirected > 0)
+ {
+ appendStringInfoString(buf, ", redirected:");
+ array_desc(buf, redirected, sizeof(OffsetNumber) * 2,
+ nredirected, &redirect_elem_desc, NULL);
+ }
+
+ if (ndead > 0)
+ {
+ appendStringInfoString(buf, ", dead:");
+ array_desc(buf, nowdead, sizeof(OffsetNumber), ndead,
+ &offset_elem_desc, NULL);
+ }
+
+ if (nunused > 0)
+ {
+ appendStringInfoString(buf, ", unused:");
+ array_desc(buf, nowunused, sizeof(OffsetNumber), nunused,
+ &offset_elem_desc, NULL);
+ }
+
+ if (nplans > 0)
+ {
+ appendStringInfoString(buf, ", plans:");
+ array_desc(buf, plans, sizeof(xl_heap_freeze_plan), nplans,
+ &plan_elem_desc, &frz_offsets);
+ }
}
}
else if (info == XLOG_HEAP2_VACUUM)
@@ -235,28 +259,6 @@ heap2_desc(StringInfo buf, XLogReaderState *record)
&offset_elem_desc, NULL);
}
}
- else if (info == XLOG_HEAP2_FREEZE_PAGE)
- {
- xl_heap_freeze_page *xlrec = (xl_heap_freeze_page *) rec;
-
- appendStringInfo(buf, "snapshotConflictHorizon: %u, nplans: %u, isCatalogRel: %c",
- xlrec->snapshotConflictHorizon, xlrec->nplans,
- xlrec->isCatalogRel ? 'T' : 'F');
-
- if (XLogRecHasBlockData(record, 0))
- {
- xl_heap_freeze_plan *plans;
- OffsetNumber *offsets;
-
- plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, NULL);
- offsets = (OffsetNumber *) ((char *) plans +
- (xlrec->nplans *
- sizeof(xl_heap_freeze_plan)));
- appendStringInfoString(buf, ", plans:");
- array_desc(buf, plans, sizeof(xl_heap_freeze_plan), xlrec->nplans,
- &plan_elem_desc, &offsets);
- }
- }
else if (info == XLOG_HEAP2_VISIBLE)
{
xl_heap_visible *xlrec = (xl_heap_visible *) rec;
@@ -361,9 +363,6 @@ heap2_identify(uint8 info)
case XLOG_HEAP2_VACUUM:
id = "VACUUM";
break;
- case XLOG_HEAP2_FREEZE_PAGE:
- id = "FREEZE_PAGE";
- break;
case XLOG_HEAP2_VISIBLE:
id = "VISIBLE";
break;
diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c
index e5ab7b78b78..f77051572fd 100644
--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -445,7 +445,6 @@ heap2_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
* Everything else here is just low level physical stuff we're not
* interested in.
*/
- case XLOG_HEAP2_FREEZE_PAGE:
case XLOG_HEAP2_PRUNE:
case XLOG_HEAP2_VACUUM:
case XLOG_HEAP2_VISIBLE:
diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h
index 6488dad5e64..fe4a8ff0620 100644
--- a/src/include/access/heapam_xlog.h
+++ b/src/include/access/heapam_xlog.h
@@ -53,11 +53,10 @@
#define XLOG_HEAP2_REWRITE 0x00
#define XLOG_HEAP2_PRUNE 0x10
#define XLOG_HEAP2_VACUUM 0x20
-#define XLOG_HEAP2_FREEZE_PAGE 0x30
-#define XLOG_HEAP2_VISIBLE 0x40
-#define XLOG_HEAP2_MULTI_INSERT 0x50
-#define XLOG_HEAP2_LOCK_UPDATED 0x60
-#define XLOG_HEAP2_NEW_CID 0x70
+#define XLOG_HEAP2_VISIBLE 0x30
+#define XLOG_HEAP2_MULTI_INSERT 0x40
+#define XLOG_HEAP2_LOCK_UPDATED 0x50
+#define XLOG_HEAP2_NEW_CID 0x60
/*
* xl_heap_insert/xl_heap_multi_insert flag values, 8 bits are available.
@@ -226,28 +225,65 @@ typedef struct xl_heap_update
#define SizeOfHeapUpdate (offsetof(xl_heap_update, new_offnum) + sizeof(OffsetNumber))
+/*
+ * This struct represents a 'freeze plan', which describes how to freeze a
+ * group of one or more heap tuples (appears in xl_heap_prune record)
+ */
+/* 0x01 was XLH_FREEZE_XMIN */
+#define XLH_FREEZE_XVAC 0x02
+#define XLH_INVALID_XVAC 0x04
+
+typedef struct xl_heap_freeze_plan
+{
+ TransactionId xmax;
+ uint16 t_infomask2;
+ uint16 t_infomask;
+ uint8 frzflags;
+
+ /* Length of individual page offset numbers array for this plan */
+ uint16 ntuples;
+} xl_heap_freeze_plan;
+
+/*
+ * As of Postgres 17, XLOG_HEAP2_PRUNE records replace
+ * XLOG_HEAP2_FREEZE_PAGE records.
+ */
+
/*
* This is what we need to know about page pruning (both during VACUUM and
* during opportunistic pruning)
*
* The array of OffsetNumbers following the fixed part of the record contains:
+ * * for each freeze plan: the freeze plan
* * for each redirected item: the item offset, then the offset redirected to
* * for each now-dead item: the item offset
* * for each now-unused item: the item offset
- * The total number of OffsetNumbers is therefore 2*nredirected+ndead+nunused.
- * Note that nunused is not explicitly stored, but may be found by reference
- * to the total record length.
+ * * for each tuple frozen by the freeze plans: the offset of the item corresponding to that tuple
+ * The total number of OffsetNumbers is therefore
+ * (2*nredirected) + ndead + nunused + (sum[plan.ntuples for plan in plans])
*
- * Acquires a full cleanup lock.
+ * Acquires a full cleanup lock if heap_page_prune_execute() must be called
*/
typedef struct xl_heap_prune
{
TransactionId snapshotConflictHorizon;
+ uint16 nplans;
uint16 nredirected;
uint16 ndead;
+ uint16 nunused;
bool isCatalogRel; /* to handle recovery conflict during logical
* decoding on standby */
- /* OFFSET NUMBERS are in the block reference 0 */
+ /*--------------------------------------------------------------------
+ * OFFSET NUMBERS and freeze plans are in the block reference 0 in the
+ * following order:
+ *
+ * * xl_heap_freeze_plan plans[nplans];
+ * * OffsetNumber redirected[2 * nredirected];
+ * * OffsetNumber nowdead[ndead];
+ * * OffsetNumber nowunused[nunused];
+ * * OffsetNumber frz_offsets[...];
+ *--------------------------------------------------------------------
+ */
} xl_heap_prune;
#define SizeOfHeapPrune (offsetof(xl_heap_prune, isCatalogRel) + sizeof(bool))
@@ -315,47 +351,6 @@ typedef struct xl_heap_inplace
#define SizeOfHeapInplace (offsetof(xl_heap_inplace, offnum) + sizeof(OffsetNumber))
-/*
- * This struct represents a 'freeze plan', which describes how to freeze a
- * group of one or more heap tuples (appears in xl_heap_freeze_page record)
- */
-/* 0x01 was XLH_FREEZE_XMIN */
-#define XLH_FREEZE_XVAC 0x02
-#define XLH_INVALID_XVAC 0x04
-
-typedef struct xl_heap_freeze_plan
-{
- TransactionId xmax;
- uint16 t_infomask2;
- uint16 t_infomask;
- uint8 frzflags;
-
- /* Length of individual page offset numbers array for this plan */
- uint16 ntuples;
-} xl_heap_freeze_plan;
-
-/*
- * This is what we need to know about a block being frozen during vacuum
- *
- * Backup block 0's data contains an array of xl_heap_freeze_plan structs
- * (with nplans elements), followed by one or more page offset number arrays.
- * Each such page offset number array corresponds to a single freeze plan
- * (REDO routine freezes corresponding heap tuples using freeze plan).
- */
-typedef struct xl_heap_freeze_page
-{
- TransactionId snapshotConflictHorizon;
- uint16 nplans;
- bool isCatalogRel; /* to handle recovery conflict during logical
- * decoding on standby */
-
- /*
- * In payload of blk 0 : FREEZE PLANS and OFFSET NUMBER ARRAY
- */
-} xl_heap_freeze_page;
-
-#define SizeOfHeapFreezePage (offsetof(xl_heap_freeze_page, isCatalogRel) + sizeof(bool))
-
/*
* This is what we need to know about setting a visibility map bit
*
--
2.40.1
--tez7m2a73jtztiij
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v4-0014-Vacuum-second-pass-emits-XLOG_HEAP2_PRUNE-record.patch"
^ permalink raw reply [nested|flat] 18+ messages in thread
* [PATCH v4 13/19] Merge prune and freeze records
@ 2024-01-07 22:55 Melanie Plageman <[email protected]>
0 siblings, 0 replies; 18+ messages in thread
From: Melanie Plageman @ 2024-01-07 22:55 UTC (permalink / raw)
Eliminate xl_heap_freeze and XLOG_HEAP2_FREEZE record. When vacuum
freezes tuples, the information needed to replay those changes is
now recorded in the xl_heap_prune record.
When both pruning and freezing is done, this means a single, combined
WAL record is emitted for both operations. This will reduce the number
of WAL records emitted.
When there are only tuples to freeze present, we can avoid taking a full
cleanup lock when replaying the record.
The XLOG_HEAP2_PRUNE record is now bigger than it was previously and
bigger than the XLOG_HEAP2_FREEZE record. A future commit will
streamline the record.
---
src/backend/access/heap/heapam.c | 146 ++++------
src/backend/access/heap/pruneheap.c | 326 ++++++++++++-----------
src/backend/access/rmgrdesc/heapdesc.c | 95 ++++---
src/backend/replication/logical/decode.c | 1 -
src/include/access/heapam_xlog.h | 97 ++++---
5 files changed, 318 insertions(+), 347 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index e47b56e7856..532868039d5 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8706,8 +8706,6 @@ ExtractReplicaIdentity(Relation relation, HeapTuple tp, bool key_required,
/*
* Handles XLOG_HEAP2_PRUNE record type.
- *
- * Acquires a full cleanup lock.
*/
static void
heap_xlog_prune(XLogReaderState *record)
@@ -8718,12 +8716,22 @@ heap_xlog_prune(XLogReaderState *record)
RelFileLocator rlocator;
BlockNumber blkno;
XLogRedoAction action;
+ bool get_cleanup_lock;
XLogRecGetBlockTag(record, 0, &rlocator, NULL, &blkno);
/*
- * We're about to remove tuples. In Hot Standby mode, ensure that there's
- * no queries running for which the removed tuples are still visible.
+ * If there are dead, redirected, or unused items set unused by
+ * heap_page_prune_and_freeze(), heap_page_prune_execute() will call
+ * PageRepairFragementation() which expects a full cleanup lock.
+ */
+ get_cleanup_lock = xlrec->nredirected > 0 ||
+ xlrec->ndead > 0 || xlrec->nunused > 0;
+
+ /*
+ * We are either about to remove tuples or freeze them. In Hot Standby
+ * mode, ensure that there's no queries running for which any removed
+ * tuples are still visible or which consider the frozen xids as running.
*/
if (InHotStandby)
ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
@@ -8731,38 +8739,69 @@ heap_xlog_prune(XLogReaderState *record)
rlocator);
/*
- * If we have a full-page image, restore it (using a cleanup lock) and
- * we're done.
+ * If we have a full-page image, restore it and we're done.
*/
- action = XLogReadBufferForRedoExtended(record, 0, RBM_NORMAL, true,
- &buffer);
+ action = XLogReadBufferForRedoExtended(record, 0, RBM_NORMAL,
+ get_cleanup_lock, &buffer);
+
if (action == BLK_NEEDS_REDO)
{
Page page = (Page) BufferGetPage(buffer);
- OffsetNumber *end;
OffsetNumber *redirected;
OffsetNumber *nowdead;
OffsetNumber *nowunused;
int nredirected;
int ndead;
int nunused;
+ int nplans;
Size datalen;
+ xl_heap_freeze_plan *plans;
+ OffsetNumber *frz_offsets;
+ int curoff = 0;
- redirected = (OffsetNumber *) XLogRecGetBlockData(record, 0, &datalen);
-
+ nplans = xlrec->nplans;
nredirected = xlrec->nredirected;
ndead = xlrec->ndead;
- end = (OffsetNumber *) ((char *) redirected + datalen);
+ nunused = xlrec->nunused;
+
+ plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, &datalen);
+ redirected = (OffsetNumber *) &plans[nplans];
nowdead = redirected + (nredirected * 2);
nowunused = nowdead + ndead;
- nunused = (end - nowunused);
- Assert(nunused >= 0);
+ frz_offsets = nowunused + nunused;
/* Update all line pointers per the record, and repair fragmentation */
- heap_page_prune_execute(buffer,
- redirected, nredirected,
- nowdead, ndead,
- nowunused, nunused);
+ if (nredirected > 0 || ndead > 0 || nunused > 0)
+ heap_page_prune_execute(buffer,
+ redirected, nredirected,
+ nowdead, ndead,
+ nowunused, nunused);
+
+ for (int p = 0; p < nplans; p++)
+ {
+ HeapTupleFreeze frz;
+
+ /*
+ * Convert freeze plan representation from WAL record into
+ * per-tuple format used by heap_execute_freeze_tuple
+ */
+ frz.xmax = plans[p].xmax;
+ frz.t_infomask2 = plans[p].t_infomask2;
+ frz.t_infomask = plans[p].t_infomask;
+ frz.frzflags = plans[p].frzflags;
+ frz.offset = InvalidOffsetNumber; /* unused, but be tidy */
+
+ for (int i = 0; i < plans[p].ntuples; i++)
+ {
+ OffsetNumber offset = frz_offsets[curoff++];
+ ItemId lp;
+ HeapTupleHeader tuple;
+
+ lp = PageGetItemId(page, offset);
+ tuple = (HeapTupleHeader) PageGetItem(page, lp);
+ heap_execute_freeze_tuple(tuple, &frz);
+ }
+ }
/*
* Note: we don't worry about updating the page's prunability hints.
@@ -9001,74 +9040,6 @@ heap_xlog_visible(XLogReaderState *record)
UnlockReleaseBuffer(vmbuffer);
}
-/*
- * Replay XLOG_HEAP2_FREEZE_PAGE records
- */
-static void
-heap_xlog_freeze_page(XLogReaderState *record)
-{
- XLogRecPtr lsn = record->EndRecPtr;
- xl_heap_freeze_page *xlrec = (xl_heap_freeze_page *) XLogRecGetData(record);
- Buffer buffer;
-
- /*
- * In Hot Standby mode, ensure that there's no queries running which still
- * consider the frozen xids as running.
- */
- if (InHotStandby)
- {
- RelFileLocator rlocator;
-
- XLogRecGetBlockTag(record, 0, &rlocator, NULL, NULL);
- ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
- xlrec->isCatalogRel,
- rlocator);
- }
-
- if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
- {
- Page page = BufferGetPage(buffer);
- xl_heap_freeze_plan *plans;
- OffsetNumber *offsets;
- int curoff = 0;
-
- plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, NULL);
- offsets = (OffsetNumber *) ((char *) plans +
- (xlrec->nplans *
- sizeof(xl_heap_freeze_plan)));
- for (int p = 0; p < xlrec->nplans; p++)
- {
- HeapTupleFreeze frz;
-
- /*
- * Convert freeze plan representation from WAL record into
- * per-tuple format used by heap_execute_freeze_tuple
- */
- frz.xmax = plans[p].xmax;
- frz.t_infomask2 = plans[p].t_infomask2;
- frz.t_infomask = plans[p].t_infomask;
- frz.frzflags = plans[p].frzflags;
- frz.offset = InvalidOffsetNumber; /* unused, but be tidy */
-
- for (int i = 0; i < plans[p].ntuples; i++)
- {
- OffsetNumber offset = offsets[curoff++];
- ItemId lp;
- HeapTupleHeader tuple;
-
- lp = PageGetItemId(page, offset);
- tuple = (HeapTupleHeader) PageGetItem(page, lp);
- heap_execute_freeze_tuple(tuple, &frz);
- }
- }
-
- PageSetLSN(page, lsn);
- MarkBufferDirty(buffer);
- }
- if (BufferIsValid(buffer))
- UnlockReleaseBuffer(buffer);
-}
-
/*
* Given an "infobits" field from an XLog record, set the correct bits in the
* given infomask and infomask2 for the tuple touched by the record.
@@ -9975,9 +9946,6 @@ heap2_redo(XLogReaderState *record)
case XLOG_HEAP2_VACUUM:
heap_xlog_vacuum(record);
break;
- case XLOG_HEAP2_FREEZE_PAGE:
- heap_xlog_freeze_page(record);
- break;
case XLOG_HEAP2_VISIBLE:
heap_xlog_visible(record);
break;
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index 7bd479cfd4e..19b50931b90 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -79,6 +79,9 @@ static void heap_prune_record_dead_or_unused(PruneState *prstate, OffsetNumber o
static void heap_prune_record_unused(PruneState *prstate, OffsetNumber offnum);
static void page_verify_redirects(Page page);
+static void log_heap_prune_and_freeze(Relation relation, Buffer buffer,
+ PruneState *prstate, PruneFreezeResult *presult);
+
/*
* Optionally prune and repair fragmentation in the specified page.
@@ -247,9 +250,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
HeapTupleData tup;
bool do_freeze;
bool do_prune;
+ bool do_hint;
bool whole_page_freezable;
bool hint_bit_fpi;
- bool prune_fpi = false;
int64 fpi_before = pgWalUsage.wal_fpi;
/*
@@ -445,10 +448,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
/*
* If checksums are enabled, heap_prune_satisfies_vacuum() may have caused
- * an FPI to be emitted. Then reset fpi_before for no prune case.
+ * an FPI to be emitted.
*/
hint_bit_fpi = fpi_before != pgWalUsage.wal_fpi;
- fpi_before = pgWalUsage.wal_fpi;
/*
* For vacuum, if the whole page will become frozen, we consider
@@ -498,14 +500,18 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
prstate.ndead > 0 ||
prstate.nunused > 0;
+ /* Record number of newly-set-LP_DEAD items for caller */
+ presult->nnewlpdead = prstate.ndead;
+
/*
- * Only incur overhead of checking if we will do an FPI if we might use
- * the information.
+ * Even if we don't prune anything, if we found a new value for the
+ * pd_prune_xid field or the page was marked full, we will update the hint
+ * bit.
*/
- if (do_prune && pagefrz)
- prune_fpi = XLogCheckBufferNeedsBackup(buffer);
+ do_hint = ((PageHeader) page)->pd_prune_xid != prstate.new_prune_xid ||
+ PageIsFull(page);
- /* Is the whole page freezable? And is there something to freeze */
+ /* Is the whole page freezable? And is there something to freeze? */
whole_page_freezable = presult->all_visible_except_removable &&
presult->all_frozen;
@@ -520,43 +526,51 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* opportunistic freeze heuristic must be improved; however, for now, try
* to approximate it.
*/
- do_freeze = pagefrz &&
- (pagefrz->freeze_required ||
- (whole_page_freezable && presult->nfrozen > 0 && (prune_fpi || hint_bit_fpi)));
+ do_freeze = false;
+ if (pagefrz)
+ {
+ if (pagefrz->freeze_required)
+ do_freeze = true;
+ else if (whole_page_freezable && presult->nfrozen > 0)
+ {
+ /*
+ * Freezing would make the page all-frozen. In this case, we will
+ * freeze if we have already emitted an FPI or will do so anyway.
+ * Be sure only to incur the overhead of checking if we will do an
+ * FPI if we may use that information.
+ */
+ if (hint_bit_fpi ||
+ ((do_prune || do_hint) && XLogCheckBufferNeedsBackup(buffer)))
+ {
+ do_freeze = true;
+ }
+ }
+ }
+ /*
+ * Validate the tuples we are considering freezing. We do this even if
+ * pruning and hint bit setting have not emitted an FPI so far because we
+ * still may emit an FPI while setting the page hint bit later. But we
+ * want to avoid doing the pre-freeze checks in a critical section.
+ */
if (do_freeze)
- {
heap_pre_freeze_checks(buffer, prstate.frozen, presult->nfrozen);
+ if (!do_freeze && (!pagefrz || !presult->all_frozen || presult->nfrozen > 0))
+ {
/*
- * We can use frz_conflict_horizon as our cutoff for conflicts when
- * the whole page is eligible to become all-frozen in the VM once
- * we're done with it. Otherwise we generate a conservative cutoff by
- * stepping back from OldestXmin.
+ * If we will neither freeze tuples on the page nor set the page all
+ * frozen in the visibility map, the page is not all-frozen and there
+ * will be no newly frozen tuples.
*/
- if (!(presult->all_visible_except_removable && presult->all_frozen))
- {
- /* Avoids false conflicts when hot_standby_feedback in use */
- presult->frz_conflict_horizon = pagefrz->cutoffs->OldestXmin;
- TransactionIdRetreat(presult->frz_conflict_horizon);
- }
+ presult->all_frozen = false;
+ presult->nfrozen = 0; /* avoid miscounts in instrumentation */
}
- /* Any error while applying the changes is critical */
START_CRIT_SECTION();
- /* Have we found any prunable items? */
- if (do_prune)
+ if (do_hint)
{
- /*
- * Apply the planned item changes, then repair page fragmentation, and
- * update the page's hint bit about whether it has free line pointers.
- */
- heap_page_prune_execute(buffer,
- prstate.redirected, prstate.nredirected,
- prstate.nowdead, prstate.ndead,
- prstate.nowunused, prstate.nunused);
-
/*
* Update the page's pd_prune_xid field to either zero, or the lowest
* XID of any soon-prunable tuple.
@@ -564,163 +578,159 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid;
/*
- * Also clear the "page is full" flag, since there's no point in
- * repeating the prune/defrag process until something else happens to
- * the page.
+ * Clear the "page is full" flag if it is set since there's no point
+ * in repeating the prune/defrag process until something else happens
+ * to the page.
*/
PageClearFull(page);
- MarkBufferDirty(buffer);
+ /*
+ * We only needed to update pd_prune_xid and clear the page-is-full
+ * hint bit, this is a non-WAL-logged hint. If we will also freeze or
+ * prune the page, we will mark the buffer dirty below.
+ */
+ if (!do_freeze && !do_prune)
+ MarkBufferDirtyHint(buffer, true);
+ }
+ if (do_prune || do_freeze)
+ {
/*
- * Emit a WAL XLOG_HEAP2_PRUNE record showing what we did
+ * Apply the planned item changes, then repair page fragmentation, and
+ * update the page's hint bit about whether it has free line pointers.
*/
- if (RelationNeedsWAL(relation))
+ if (do_prune)
{
- xl_heap_prune xlrec;
- XLogRecPtr recptr;
-
- xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
- xlrec.nredirected = prstate.nredirected;
- xlrec.ndead = prstate.ndead;
-
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, SizeOfHeapPrune);
-
- XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
+ heap_page_prune_execute(buffer,
+ prstate.redirected, prstate.nredirected,
+ prstate.nowdead, prstate.ndead,
+ prstate.nowunused, prstate.nunused);
+ }
+ if (do_freeze)
+ {
/*
- * The OffsetNumber arrays are not actually in the buffer, but we
- * pretend that they are. When XLogInsert stores the whole
- * buffer, the offset arrays need not be stored too.
+ * We can use frz_conflict_horizon as our cutoff for conflicts
+ * when the whole page is eligible to become all-frozen in the VM
+ * once we're done with it. Otherwise we generate a conservative
+ * cutoff by stepping back from OldestXmin. This avoids false
+ * conflicts when hot_standby_feedback is in use.
*/
- if (prstate.nredirected > 0)
- XLogRegisterBufData(0, (char *) prstate.redirected,
- prstate.nredirected *
- sizeof(OffsetNumber) * 2);
-
- if (prstate.ndead > 0)
- XLogRegisterBufData(0, (char *) prstate.nowdead,
- prstate.ndead * sizeof(OffsetNumber));
-
- if (prstate.nunused > 0)
- XLogRegisterBufData(0, (char *) prstate.nowunused,
- prstate.nunused * sizeof(OffsetNumber));
+ if (!(presult->all_visible_except_removable && presult->all_frozen))
+ {
+ presult->frz_conflict_horizon = pagefrz->cutoffs->OldestXmin;
+ TransactionIdRetreat(presult->frz_conflict_horizon);
+ }
+ heap_freeze_prepared_tuples(buffer, prstate.frozen, presult->nfrozen);
+ }
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
+ MarkBufferDirty(buffer);
- PageSetLSN(BufferGetPage(buffer), recptr);
- }
- }
- else
- {
/*
- * If we didn't prune anything, but have found a new value for the
- * pd_prune_xid field, update it and mark the buffer dirty. This is
- * treated as a non-WAL-logged hint.
- *
- * Also clear the "page is full" flag if it is set, since there's no
- * point in repeating the prune/defrag process until something else
- * happens to the page.
+ * Emit a WAL XLOG_HEAP2_PRUNE record showing what we did
*/
- if (((PageHeader) page)->pd_prune_xid != prstate.new_prune_xid ||
- PageIsFull(page))
- {
- ((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid;
- PageClearFull(page);
- MarkBufferDirtyHint(buffer, true);
- }
+ if (RelationNeedsWAL(relation))
+ log_heap_prune_and_freeze(relation, buffer, &prstate, presult);
}
END_CRIT_SECTION();
- /* Record number of newly-set-LP_DEAD items for caller */
- presult->nnewlpdead = prstate.ndead;
-
- if (do_freeze)
+ /*
+ * If we froze tuples on the page, the caller can advance relfrozenxid and
+ * relminmxid to the values in pagefrz->FreezePageRelfrozenXid and
+ * pagefrz->FreezePageRelminMxid. Otherwise, it is only safe to advance to
+ * the values in pagefrz->NoFreezePage[RelfrozenXid|RelminMxid]
+ */
+ if (pagefrz)
{
- START_CRIT_SECTION();
+ if (presult->nfrozen > 0)
+ {
+ presult->new_relfrozenxid = pagefrz->FreezePageRelfrozenXid;
+ presult->new_relminmxid = pagefrz->FreezePageRelminMxid;
+ }
+ else
+ {
+ presult->new_relfrozenxid = pagefrz->NoFreezePageRelfrozenXid;
+ presult->new_relminmxid = pagefrz->NoFreezePageRelminMxid;
+ }
+ }
+}
- Assert(presult->nfrozen > 0);
- heap_freeze_prepared_tuples(buffer, prstate.frozen, presult->nfrozen);
+static void
+log_heap_prune_and_freeze(Relation relation, Buffer buffer,
+ PruneState *prstate, PruneFreezeResult *presult)
+{
+ xl_heap_prune xlrec;
+ XLogRecPtr recptr;
- MarkBufferDirty(buffer);
+ xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
+ OffsetNumber offsets[MaxHeapTuplesPerPage];
+ bool do_freeze = presult->nfrozen > 0;
- /* Now WAL-log freezing if necessary */
- if (RelationNeedsWAL(relation))
- {
- xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
- OffsetNumber offsets[MaxHeapTuplesPerPage];
- int nplans;
- xl_heap_freeze_page xlrec;
- XLogRecPtr recptr;
+ xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
+ xlrec.nredirected = prstate->nredirected;
+ xlrec.ndead = prstate->ndead;
+ xlrec.nunused = prstate->nunused;
+ xlrec.nplans = 0;
- /*
- * Prepare deduplicated representation for use in WAL record
- * Destructively sorts tuples array in-place.
- */
- nplans = heap_log_freeze_plan(prstate.frozen, presult->nfrozen, plans, offsets);
+ /*
+ * The snapshotConflictHorizon for the whole record should be the most
+ * conservative of all the horizons calculated for any of the possible
+ * modifications. If this record will prune tuples, any transactions on
+ * the standby older than the youngest xmax of the most recently removed
+ * tuple this record will prune will conflict. If this record will freeze
+ * tuples, any transactions on the standby with xids older than the
+ * youngest tuple this record will freeze will conflict.
+ */
+ if (do_freeze)
+ xlrec.snapshotConflictHorizon = Max(prstate->snapshotConflictHorizon,
+ presult->frz_conflict_horizon);
+ else
+ xlrec.snapshotConflictHorizon = prstate->snapshotConflictHorizon;
- xlrec.snapshotConflictHorizon = presult->frz_conflict_horizon;
- xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.nplans = nplans;
+ /*
+ * Prepare deduplicated representation for use in WAL record Destructively
+ * sorts tuples array in-place.
+ */
+ if (do_freeze)
+ xlrec.nplans = heap_log_freeze_plan(prstate->frozen,
+ presult->nfrozen, plans, offsets);
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, SizeOfHeapFreezePage);
+ XLogBeginInsert();
+ XLogRegisterData((char *) &xlrec, SizeOfHeapPrune);
- /*
- * The freeze plan array and offset array are not actually in the
- * buffer, but pretend that they are. When XLogInsert stores the
- * whole buffer, the arrays need not be stored too.
- */
- XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
- XLogRegisterBufData(0, (char *) plans,
- nplans * sizeof(xl_heap_freeze_plan));
- XLogRegisterBufData(0, (char *) offsets,
- presult->nfrozen * sizeof(OffsetNumber));
+ XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_FREEZE_PAGE);
+ /*
+ * The OffsetNumber arrays are not actually in the buffer, but we pretend
+ * that they are. When XLogInsert stores the whole buffer, the offset
+ * arrays need not be stored too.
+ */
+ if (xlrec.nplans > 0)
+ XLogRegisterBufData(0, (char *) plans,
+ xlrec.nplans * sizeof(xl_heap_freeze_plan));
- PageSetLSN(page, recptr);
- }
+ if (prstate->nredirected > 0)
+ XLogRegisterBufData(0, (char *) prstate->redirected,
+ prstate->nredirected *
+ sizeof(OffsetNumber) * 2);
- END_CRIT_SECTION();
- }
- else if (!pagefrz || !presult->all_frozen || presult->nfrozen > 0)
- {
- /*
- * If we will neither freeze tuples on the page nor set the page all
- * frozen in the visibility map, the page is not all frozen and there
- * will be no newly frozen tuples.
- */
- presult->all_frozen = false;
- presult->nfrozen = 0; /* avoid miscounts in instrumentation */
- }
+ if (prstate->ndead > 0)
+ XLogRegisterBufData(0, (char *) prstate->nowdead,
+ prstate->ndead * sizeof(OffsetNumber));
- /* Caller won't update new_relfrozenxid and new_relminmxid */
- if (!pagefrz)
- return;
+ if (prstate->nunused > 0)
+ XLogRegisterBufData(0, (char *) prstate->nowunused,
+ prstate->nunused * sizeof(OffsetNumber));
+ if (xlrec.nplans > 0)
+ XLogRegisterBufData(0, (char *) offsets,
+ presult->nfrozen * sizeof(OffsetNumber));
- /*
- * If we will freeze tuples on the page or, even if we don't freeze tuples
- * on the page, if we will set the page all-frozen in the visibility map,
- * we can advance relfrozenxid and relminmxid to the values in
- * pagefrz->FreezePageRelfrozenXid and pagefrz->FreezePageRelminMxid.
- */
- if (presult->all_frozen || presult->nfrozen > 0)
- {
- presult->new_relfrozenxid = pagefrz->FreezePageRelfrozenXid;
- presult->new_relminmxid = pagefrz->FreezePageRelminMxid;
- }
- else
- {
- presult->new_relfrozenxid = pagefrz->NoFreezePageRelfrozenXid;
- presult->new_relminmxid = pagefrz->NoFreezePageRelminMxid;
- }
-}
+ recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
+ PageSetLSN(BufferGetPage(buffer), recptr);
+}
/*
* Perform visibility checks for heap pruning.
diff --git a/src/backend/access/rmgrdesc/heapdesc.c b/src/backend/access/rmgrdesc/heapdesc.c
index 36a3d83c8c2..9f0a0341d40 100644
--- a/src/backend/access/rmgrdesc/heapdesc.c
+++ b/src/backend/access/rmgrdesc/heapdesc.c
@@ -179,43 +179,67 @@ heap2_desc(StringInfo buf, XLogReaderState *record)
{
xl_heap_prune *xlrec = (xl_heap_prune *) rec;
- appendStringInfo(buf, "snapshotConflictHorizon: %u, nredirected: %u, ndead: %u, isCatalogRel: %c",
+ appendStringInfo(buf, "snapshotConflictHorizon: %u, isCatalogRel: %c",
xlrec->snapshotConflictHorizon,
- xlrec->nredirected,
- xlrec->ndead,
xlrec->isCatalogRel ? 'T' : 'F');
if (XLogRecHasBlockData(record, 0))
{
- OffsetNumber *end;
OffsetNumber *redirected;
OffsetNumber *nowdead;
OffsetNumber *nowunused;
int nredirected;
+ int ndead;
int nunused;
+ int nplans;
Size datalen;
+ xl_heap_freeze_plan *plans;
+ OffsetNumber *frz_offsets;
- redirected = (OffsetNumber *) XLogRecGetBlockData(record, 0,
- &datalen);
-
+ nplans = xlrec->nplans;
nredirected = xlrec->nredirected;
- end = (OffsetNumber *) ((char *) redirected + datalen);
- nowdead = redirected + (nredirected * 2);
- nowunused = nowdead + xlrec->ndead;
- nunused = (end - nowunused);
- Assert(nunused >= 0);
+ ndead = xlrec->ndead;
+ nunused = xlrec->nunused;
- appendStringInfo(buf, ", nunused: %d", nunused);
-
- appendStringInfoString(buf, ", redirected:");
- array_desc(buf, redirected, sizeof(OffsetNumber) * 2,
- nredirected, &redirect_elem_desc, NULL);
- appendStringInfoString(buf, ", dead:");
- array_desc(buf, nowdead, sizeof(OffsetNumber), xlrec->ndead,
- &offset_elem_desc, NULL);
- appendStringInfoString(buf, ", unused:");
- array_desc(buf, nowunused, sizeof(OffsetNumber), nunused,
- &offset_elem_desc, NULL);
+ plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, &datalen);
+ redirected = (OffsetNumber *) &plans[nplans];
+ nowdead = redirected + (nredirected * 2);
+ nowunused = nowdead + ndead;
+ frz_offsets = nowunused + nunused;
+
+ appendStringInfo(buf, ", nredirected: %u, ndead: %u, nunused: %u, nplans: %u,",
+ nredirected,
+ ndead,
+ nunused,
+ nplans);
+
+ if (nredirected > 0)
+ {
+ appendStringInfoString(buf, ", redirected:");
+ array_desc(buf, redirected, sizeof(OffsetNumber) * 2,
+ nredirected, &redirect_elem_desc, NULL);
+ }
+
+ if (ndead > 0)
+ {
+ appendStringInfoString(buf, ", dead:");
+ array_desc(buf, nowdead, sizeof(OffsetNumber), ndead,
+ &offset_elem_desc, NULL);
+ }
+
+ if (nunused > 0)
+ {
+ appendStringInfoString(buf, ", unused:");
+ array_desc(buf, nowunused, sizeof(OffsetNumber), nunused,
+ &offset_elem_desc, NULL);
+ }
+
+ if (nplans > 0)
+ {
+ appendStringInfoString(buf, ", plans:");
+ array_desc(buf, plans, sizeof(xl_heap_freeze_plan), nplans,
+ &plan_elem_desc, &frz_offsets);
+ }
}
}
else if (info == XLOG_HEAP2_VACUUM)
@@ -235,28 +259,6 @@ heap2_desc(StringInfo buf, XLogReaderState *record)
&offset_elem_desc, NULL);
}
}
- else if (info == XLOG_HEAP2_FREEZE_PAGE)
- {
- xl_heap_freeze_page *xlrec = (xl_heap_freeze_page *) rec;
-
- appendStringInfo(buf, "snapshotConflictHorizon: %u, nplans: %u, isCatalogRel: %c",
- xlrec->snapshotConflictHorizon, xlrec->nplans,
- xlrec->isCatalogRel ? 'T' : 'F');
-
- if (XLogRecHasBlockData(record, 0))
- {
- xl_heap_freeze_plan *plans;
- OffsetNumber *offsets;
-
- plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, NULL);
- offsets = (OffsetNumber *) ((char *) plans +
- (xlrec->nplans *
- sizeof(xl_heap_freeze_plan)));
- appendStringInfoString(buf, ", plans:");
- array_desc(buf, plans, sizeof(xl_heap_freeze_plan), xlrec->nplans,
- &plan_elem_desc, &offsets);
- }
- }
else if (info == XLOG_HEAP2_VISIBLE)
{
xl_heap_visible *xlrec = (xl_heap_visible *) rec;
@@ -361,9 +363,6 @@ heap2_identify(uint8 info)
case XLOG_HEAP2_VACUUM:
id = "VACUUM";
break;
- case XLOG_HEAP2_FREEZE_PAGE:
- id = "FREEZE_PAGE";
- break;
case XLOG_HEAP2_VISIBLE:
id = "VISIBLE";
break;
diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c
index e5ab7b78b78..f77051572fd 100644
--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -445,7 +445,6 @@ heap2_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
* Everything else here is just low level physical stuff we're not
* interested in.
*/
- case XLOG_HEAP2_FREEZE_PAGE:
case XLOG_HEAP2_PRUNE:
case XLOG_HEAP2_VACUUM:
case XLOG_HEAP2_VISIBLE:
diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h
index 6488dad5e64..fe4a8ff0620 100644
--- a/src/include/access/heapam_xlog.h
+++ b/src/include/access/heapam_xlog.h
@@ -53,11 +53,10 @@
#define XLOG_HEAP2_REWRITE 0x00
#define XLOG_HEAP2_PRUNE 0x10
#define XLOG_HEAP2_VACUUM 0x20
-#define XLOG_HEAP2_FREEZE_PAGE 0x30
-#define XLOG_HEAP2_VISIBLE 0x40
-#define XLOG_HEAP2_MULTI_INSERT 0x50
-#define XLOG_HEAP2_LOCK_UPDATED 0x60
-#define XLOG_HEAP2_NEW_CID 0x70
+#define XLOG_HEAP2_VISIBLE 0x30
+#define XLOG_HEAP2_MULTI_INSERT 0x40
+#define XLOG_HEAP2_LOCK_UPDATED 0x50
+#define XLOG_HEAP2_NEW_CID 0x60
/*
* xl_heap_insert/xl_heap_multi_insert flag values, 8 bits are available.
@@ -226,28 +225,65 @@ typedef struct xl_heap_update
#define SizeOfHeapUpdate (offsetof(xl_heap_update, new_offnum) + sizeof(OffsetNumber))
+/*
+ * This struct represents a 'freeze plan', which describes how to freeze a
+ * group of one or more heap tuples (appears in xl_heap_prune record)
+ */
+/* 0x01 was XLH_FREEZE_XMIN */
+#define XLH_FREEZE_XVAC 0x02
+#define XLH_INVALID_XVAC 0x04
+
+typedef struct xl_heap_freeze_plan
+{
+ TransactionId xmax;
+ uint16 t_infomask2;
+ uint16 t_infomask;
+ uint8 frzflags;
+
+ /* Length of individual page offset numbers array for this plan */
+ uint16 ntuples;
+} xl_heap_freeze_plan;
+
+/*
+ * As of Postgres 17, XLOG_HEAP2_PRUNE records replace
+ * XLOG_HEAP2_FREEZE_PAGE records.
+ */
+
/*
* This is what we need to know about page pruning (both during VACUUM and
* during opportunistic pruning)
*
* The array of OffsetNumbers following the fixed part of the record contains:
+ * * for each freeze plan: the freeze plan
* * for each redirected item: the item offset, then the offset redirected to
* * for each now-dead item: the item offset
* * for each now-unused item: the item offset
- * The total number of OffsetNumbers is therefore 2*nredirected+ndead+nunused.
- * Note that nunused is not explicitly stored, but may be found by reference
- * to the total record length.
+ * * for each tuple frozen by the freeze plans: the offset of the item corresponding to that tuple
+ * The total number of OffsetNumbers is therefore
+ * (2*nredirected) + ndead + nunused + (sum[plan.ntuples for plan in plans])
*
- * Acquires a full cleanup lock.
+ * Acquires a full cleanup lock if heap_page_prune_execute() must be called
*/
typedef struct xl_heap_prune
{
TransactionId snapshotConflictHorizon;
+ uint16 nplans;
uint16 nredirected;
uint16 ndead;
+ uint16 nunused;
bool isCatalogRel; /* to handle recovery conflict during logical
* decoding on standby */
- /* OFFSET NUMBERS are in the block reference 0 */
+ /*--------------------------------------------------------------------
+ * OFFSET NUMBERS and freeze plans are in the block reference 0 in the
+ * following order:
+ *
+ * * xl_heap_freeze_plan plans[nplans];
+ * * OffsetNumber redirected[2 * nredirected];
+ * * OffsetNumber nowdead[ndead];
+ * * OffsetNumber nowunused[nunused];
+ * * OffsetNumber frz_offsets[...];
+ *--------------------------------------------------------------------
+ */
} xl_heap_prune;
#define SizeOfHeapPrune (offsetof(xl_heap_prune, isCatalogRel) + sizeof(bool))
@@ -315,47 +351,6 @@ typedef struct xl_heap_inplace
#define SizeOfHeapInplace (offsetof(xl_heap_inplace, offnum) + sizeof(OffsetNumber))
-/*
- * This struct represents a 'freeze plan', which describes how to freeze a
- * group of one or more heap tuples (appears in xl_heap_freeze_page record)
- */
-/* 0x01 was XLH_FREEZE_XMIN */
-#define XLH_FREEZE_XVAC 0x02
-#define XLH_INVALID_XVAC 0x04
-
-typedef struct xl_heap_freeze_plan
-{
- TransactionId xmax;
- uint16 t_infomask2;
- uint16 t_infomask;
- uint8 frzflags;
-
- /* Length of individual page offset numbers array for this plan */
- uint16 ntuples;
-} xl_heap_freeze_plan;
-
-/*
- * This is what we need to know about a block being frozen during vacuum
- *
- * Backup block 0's data contains an array of xl_heap_freeze_plan structs
- * (with nplans elements), followed by one or more page offset number arrays.
- * Each such page offset number array corresponds to a single freeze plan
- * (REDO routine freezes corresponding heap tuples using freeze plan).
- */
-typedef struct xl_heap_freeze_page
-{
- TransactionId snapshotConflictHorizon;
- uint16 nplans;
- bool isCatalogRel; /* to handle recovery conflict during logical
- * decoding on standby */
-
- /*
- * In payload of blk 0 : FREEZE PLANS and OFFSET NUMBER ARRAY
- */
-} xl_heap_freeze_page;
-
-#define SizeOfHeapFreezePage (offsetof(xl_heap_freeze_page, isCatalogRel) + sizeof(bool))
-
/*
* This is what we need to know about setting a visibility map bit
*
--
2.40.1
--tez7m2a73jtztiij
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v4-0014-Vacuum-second-pass-emits-XLOG_HEAP2_PRUNE-record.patch"
^ permalink raw reply [nested|flat] 18+ messages in thread
* [PATCH v4 13/19] Merge prune and freeze records
@ 2024-01-07 22:55 Melanie Plageman <[email protected]>
0 siblings, 0 replies; 18+ messages in thread
From: Melanie Plageman @ 2024-01-07 22:55 UTC (permalink / raw)
Eliminate xl_heap_freeze and XLOG_HEAP2_FREEZE record. When vacuum
freezes tuples, the information needed to replay those changes is
now recorded in the xl_heap_prune record.
When both pruning and freezing is done, this means a single, combined
WAL record is emitted for both operations. This will reduce the number
of WAL records emitted.
When there are only tuples to freeze present, we can avoid taking a full
cleanup lock when replaying the record.
The XLOG_HEAP2_PRUNE record is now bigger than it was previously and
bigger than the XLOG_HEAP2_FREEZE record. A future commit will
streamline the record.
---
src/backend/access/heap/heapam.c | 146 ++++------
src/backend/access/heap/pruneheap.c | 326 ++++++++++++-----------
src/backend/access/rmgrdesc/heapdesc.c | 95 ++++---
src/backend/replication/logical/decode.c | 1 -
src/include/access/heapam_xlog.h | 97 ++++---
5 files changed, 318 insertions(+), 347 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index e47b56e7856..532868039d5 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8706,8 +8706,6 @@ ExtractReplicaIdentity(Relation relation, HeapTuple tp, bool key_required,
/*
* Handles XLOG_HEAP2_PRUNE record type.
- *
- * Acquires a full cleanup lock.
*/
static void
heap_xlog_prune(XLogReaderState *record)
@@ -8718,12 +8716,22 @@ heap_xlog_prune(XLogReaderState *record)
RelFileLocator rlocator;
BlockNumber blkno;
XLogRedoAction action;
+ bool get_cleanup_lock;
XLogRecGetBlockTag(record, 0, &rlocator, NULL, &blkno);
/*
- * We're about to remove tuples. In Hot Standby mode, ensure that there's
- * no queries running for which the removed tuples are still visible.
+ * If there are dead, redirected, or unused items set unused by
+ * heap_page_prune_and_freeze(), heap_page_prune_execute() will call
+ * PageRepairFragementation() which expects a full cleanup lock.
+ */
+ get_cleanup_lock = xlrec->nredirected > 0 ||
+ xlrec->ndead > 0 || xlrec->nunused > 0;
+
+ /*
+ * We are either about to remove tuples or freeze them. In Hot Standby
+ * mode, ensure that there's no queries running for which any removed
+ * tuples are still visible or which consider the frozen xids as running.
*/
if (InHotStandby)
ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
@@ -8731,38 +8739,69 @@ heap_xlog_prune(XLogReaderState *record)
rlocator);
/*
- * If we have a full-page image, restore it (using a cleanup lock) and
- * we're done.
+ * If we have a full-page image, restore it and we're done.
*/
- action = XLogReadBufferForRedoExtended(record, 0, RBM_NORMAL, true,
- &buffer);
+ action = XLogReadBufferForRedoExtended(record, 0, RBM_NORMAL,
+ get_cleanup_lock, &buffer);
+
if (action == BLK_NEEDS_REDO)
{
Page page = (Page) BufferGetPage(buffer);
- OffsetNumber *end;
OffsetNumber *redirected;
OffsetNumber *nowdead;
OffsetNumber *nowunused;
int nredirected;
int ndead;
int nunused;
+ int nplans;
Size datalen;
+ xl_heap_freeze_plan *plans;
+ OffsetNumber *frz_offsets;
+ int curoff = 0;
- redirected = (OffsetNumber *) XLogRecGetBlockData(record, 0, &datalen);
-
+ nplans = xlrec->nplans;
nredirected = xlrec->nredirected;
ndead = xlrec->ndead;
- end = (OffsetNumber *) ((char *) redirected + datalen);
+ nunused = xlrec->nunused;
+
+ plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, &datalen);
+ redirected = (OffsetNumber *) &plans[nplans];
nowdead = redirected + (nredirected * 2);
nowunused = nowdead + ndead;
- nunused = (end - nowunused);
- Assert(nunused >= 0);
+ frz_offsets = nowunused + nunused;
/* Update all line pointers per the record, and repair fragmentation */
- heap_page_prune_execute(buffer,
- redirected, nredirected,
- nowdead, ndead,
- nowunused, nunused);
+ if (nredirected > 0 || ndead > 0 || nunused > 0)
+ heap_page_prune_execute(buffer,
+ redirected, nredirected,
+ nowdead, ndead,
+ nowunused, nunused);
+
+ for (int p = 0; p < nplans; p++)
+ {
+ HeapTupleFreeze frz;
+
+ /*
+ * Convert freeze plan representation from WAL record into
+ * per-tuple format used by heap_execute_freeze_tuple
+ */
+ frz.xmax = plans[p].xmax;
+ frz.t_infomask2 = plans[p].t_infomask2;
+ frz.t_infomask = plans[p].t_infomask;
+ frz.frzflags = plans[p].frzflags;
+ frz.offset = InvalidOffsetNumber; /* unused, but be tidy */
+
+ for (int i = 0; i < plans[p].ntuples; i++)
+ {
+ OffsetNumber offset = frz_offsets[curoff++];
+ ItemId lp;
+ HeapTupleHeader tuple;
+
+ lp = PageGetItemId(page, offset);
+ tuple = (HeapTupleHeader) PageGetItem(page, lp);
+ heap_execute_freeze_tuple(tuple, &frz);
+ }
+ }
/*
* Note: we don't worry about updating the page's prunability hints.
@@ -9001,74 +9040,6 @@ heap_xlog_visible(XLogReaderState *record)
UnlockReleaseBuffer(vmbuffer);
}
-/*
- * Replay XLOG_HEAP2_FREEZE_PAGE records
- */
-static void
-heap_xlog_freeze_page(XLogReaderState *record)
-{
- XLogRecPtr lsn = record->EndRecPtr;
- xl_heap_freeze_page *xlrec = (xl_heap_freeze_page *) XLogRecGetData(record);
- Buffer buffer;
-
- /*
- * In Hot Standby mode, ensure that there's no queries running which still
- * consider the frozen xids as running.
- */
- if (InHotStandby)
- {
- RelFileLocator rlocator;
-
- XLogRecGetBlockTag(record, 0, &rlocator, NULL, NULL);
- ResolveRecoveryConflictWithSnapshot(xlrec->snapshotConflictHorizon,
- xlrec->isCatalogRel,
- rlocator);
- }
-
- if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
- {
- Page page = BufferGetPage(buffer);
- xl_heap_freeze_plan *plans;
- OffsetNumber *offsets;
- int curoff = 0;
-
- plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, NULL);
- offsets = (OffsetNumber *) ((char *) plans +
- (xlrec->nplans *
- sizeof(xl_heap_freeze_plan)));
- for (int p = 0; p < xlrec->nplans; p++)
- {
- HeapTupleFreeze frz;
-
- /*
- * Convert freeze plan representation from WAL record into
- * per-tuple format used by heap_execute_freeze_tuple
- */
- frz.xmax = plans[p].xmax;
- frz.t_infomask2 = plans[p].t_infomask2;
- frz.t_infomask = plans[p].t_infomask;
- frz.frzflags = plans[p].frzflags;
- frz.offset = InvalidOffsetNumber; /* unused, but be tidy */
-
- for (int i = 0; i < plans[p].ntuples; i++)
- {
- OffsetNumber offset = offsets[curoff++];
- ItemId lp;
- HeapTupleHeader tuple;
-
- lp = PageGetItemId(page, offset);
- tuple = (HeapTupleHeader) PageGetItem(page, lp);
- heap_execute_freeze_tuple(tuple, &frz);
- }
- }
-
- PageSetLSN(page, lsn);
- MarkBufferDirty(buffer);
- }
- if (BufferIsValid(buffer))
- UnlockReleaseBuffer(buffer);
-}
-
/*
* Given an "infobits" field from an XLog record, set the correct bits in the
* given infomask and infomask2 for the tuple touched by the record.
@@ -9975,9 +9946,6 @@ heap2_redo(XLogReaderState *record)
case XLOG_HEAP2_VACUUM:
heap_xlog_vacuum(record);
break;
- case XLOG_HEAP2_FREEZE_PAGE:
- heap_xlog_freeze_page(record);
- break;
case XLOG_HEAP2_VISIBLE:
heap_xlog_visible(record);
break;
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index 7bd479cfd4e..19b50931b90 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -79,6 +79,9 @@ static void heap_prune_record_dead_or_unused(PruneState *prstate, OffsetNumber o
static void heap_prune_record_unused(PruneState *prstate, OffsetNumber offnum);
static void page_verify_redirects(Page page);
+static void log_heap_prune_and_freeze(Relation relation, Buffer buffer,
+ PruneState *prstate, PruneFreezeResult *presult);
+
/*
* Optionally prune and repair fragmentation in the specified page.
@@ -247,9 +250,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
HeapTupleData tup;
bool do_freeze;
bool do_prune;
+ bool do_hint;
bool whole_page_freezable;
bool hint_bit_fpi;
- bool prune_fpi = false;
int64 fpi_before = pgWalUsage.wal_fpi;
/*
@@ -445,10 +448,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
/*
* If checksums are enabled, heap_prune_satisfies_vacuum() may have caused
- * an FPI to be emitted. Then reset fpi_before for no prune case.
+ * an FPI to be emitted.
*/
hint_bit_fpi = fpi_before != pgWalUsage.wal_fpi;
- fpi_before = pgWalUsage.wal_fpi;
/*
* For vacuum, if the whole page will become frozen, we consider
@@ -498,14 +500,18 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
prstate.ndead > 0 ||
prstate.nunused > 0;
+ /* Record number of newly-set-LP_DEAD items for caller */
+ presult->nnewlpdead = prstate.ndead;
+
/*
- * Only incur overhead of checking if we will do an FPI if we might use
- * the information.
+ * Even if we don't prune anything, if we found a new value for the
+ * pd_prune_xid field or the page was marked full, we will update the hint
+ * bit.
*/
- if (do_prune && pagefrz)
- prune_fpi = XLogCheckBufferNeedsBackup(buffer);
+ do_hint = ((PageHeader) page)->pd_prune_xid != prstate.new_prune_xid ||
+ PageIsFull(page);
- /* Is the whole page freezable? And is there something to freeze */
+ /* Is the whole page freezable? And is there something to freeze? */
whole_page_freezable = presult->all_visible_except_removable &&
presult->all_frozen;
@@ -520,43 +526,51 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* opportunistic freeze heuristic must be improved; however, for now, try
* to approximate it.
*/
- do_freeze = pagefrz &&
- (pagefrz->freeze_required ||
- (whole_page_freezable && presult->nfrozen > 0 && (prune_fpi || hint_bit_fpi)));
+ do_freeze = false;
+ if (pagefrz)
+ {
+ if (pagefrz->freeze_required)
+ do_freeze = true;
+ else if (whole_page_freezable && presult->nfrozen > 0)
+ {
+ /*
+ * Freezing would make the page all-frozen. In this case, we will
+ * freeze if we have already emitted an FPI or will do so anyway.
+ * Be sure only to incur the overhead of checking if we will do an
+ * FPI if we may use that information.
+ */
+ if (hint_bit_fpi ||
+ ((do_prune || do_hint) && XLogCheckBufferNeedsBackup(buffer)))
+ {
+ do_freeze = true;
+ }
+ }
+ }
+ /*
+ * Validate the tuples we are considering freezing. We do this even if
+ * pruning and hint bit setting have not emitted an FPI so far because we
+ * still may emit an FPI while setting the page hint bit later. But we
+ * want to avoid doing the pre-freeze checks in a critical section.
+ */
if (do_freeze)
- {
heap_pre_freeze_checks(buffer, prstate.frozen, presult->nfrozen);
+ if (!do_freeze && (!pagefrz || !presult->all_frozen || presult->nfrozen > 0))
+ {
/*
- * We can use frz_conflict_horizon as our cutoff for conflicts when
- * the whole page is eligible to become all-frozen in the VM once
- * we're done with it. Otherwise we generate a conservative cutoff by
- * stepping back from OldestXmin.
+ * If we will neither freeze tuples on the page nor set the page all
+ * frozen in the visibility map, the page is not all-frozen and there
+ * will be no newly frozen tuples.
*/
- if (!(presult->all_visible_except_removable && presult->all_frozen))
- {
- /* Avoids false conflicts when hot_standby_feedback in use */
- presult->frz_conflict_horizon = pagefrz->cutoffs->OldestXmin;
- TransactionIdRetreat(presult->frz_conflict_horizon);
- }
+ presult->all_frozen = false;
+ presult->nfrozen = 0; /* avoid miscounts in instrumentation */
}
- /* Any error while applying the changes is critical */
START_CRIT_SECTION();
- /* Have we found any prunable items? */
- if (do_prune)
+ if (do_hint)
{
- /*
- * Apply the planned item changes, then repair page fragmentation, and
- * update the page's hint bit about whether it has free line pointers.
- */
- heap_page_prune_execute(buffer,
- prstate.redirected, prstate.nredirected,
- prstate.nowdead, prstate.ndead,
- prstate.nowunused, prstate.nunused);
-
/*
* Update the page's pd_prune_xid field to either zero, or the lowest
* XID of any soon-prunable tuple.
@@ -564,163 +578,159 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid;
/*
- * Also clear the "page is full" flag, since there's no point in
- * repeating the prune/defrag process until something else happens to
- * the page.
+ * Clear the "page is full" flag if it is set since there's no point
+ * in repeating the prune/defrag process until something else happens
+ * to the page.
*/
PageClearFull(page);
- MarkBufferDirty(buffer);
+ /*
+ * We only needed to update pd_prune_xid and clear the page-is-full
+ * hint bit, this is a non-WAL-logged hint. If we will also freeze or
+ * prune the page, we will mark the buffer dirty below.
+ */
+ if (!do_freeze && !do_prune)
+ MarkBufferDirtyHint(buffer, true);
+ }
+ if (do_prune || do_freeze)
+ {
/*
- * Emit a WAL XLOG_HEAP2_PRUNE record showing what we did
+ * Apply the planned item changes, then repair page fragmentation, and
+ * update the page's hint bit about whether it has free line pointers.
*/
- if (RelationNeedsWAL(relation))
+ if (do_prune)
{
- xl_heap_prune xlrec;
- XLogRecPtr recptr;
-
- xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
- xlrec.nredirected = prstate.nredirected;
- xlrec.ndead = prstate.ndead;
-
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, SizeOfHeapPrune);
-
- XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
+ heap_page_prune_execute(buffer,
+ prstate.redirected, prstate.nredirected,
+ prstate.nowdead, prstate.ndead,
+ prstate.nowunused, prstate.nunused);
+ }
+ if (do_freeze)
+ {
/*
- * The OffsetNumber arrays are not actually in the buffer, but we
- * pretend that they are. When XLogInsert stores the whole
- * buffer, the offset arrays need not be stored too.
+ * We can use frz_conflict_horizon as our cutoff for conflicts
+ * when the whole page is eligible to become all-frozen in the VM
+ * once we're done with it. Otherwise we generate a conservative
+ * cutoff by stepping back from OldestXmin. This avoids false
+ * conflicts when hot_standby_feedback is in use.
*/
- if (prstate.nredirected > 0)
- XLogRegisterBufData(0, (char *) prstate.redirected,
- prstate.nredirected *
- sizeof(OffsetNumber) * 2);
-
- if (prstate.ndead > 0)
- XLogRegisterBufData(0, (char *) prstate.nowdead,
- prstate.ndead * sizeof(OffsetNumber));
-
- if (prstate.nunused > 0)
- XLogRegisterBufData(0, (char *) prstate.nowunused,
- prstate.nunused * sizeof(OffsetNumber));
+ if (!(presult->all_visible_except_removable && presult->all_frozen))
+ {
+ presult->frz_conflict_horizon = pagefrz->cutoffs->OldestXmin;
+ TransactionIdRetreat(presult->frz_conflict_horizon);
+ }
+ heap_freeze_prepared_tuples(buffer, prstate.frozen, presult->nfrozen);
+ }
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
+ MarkBufferDirty(buffer);
- PageSetLSN(BufferGetPage(buffer), recptr);
- }
- }
- else
- {
/*
- * If we didn't prune anything, but have found a new value for the
- * pd_prune_xid field, update it and mark the buffer dirty. This is
- * treated as a non-WAL-logged hint.
- *
- * Also clear the "page is full" flag if it is set, since there's no
- * point in repeating the prune/defrag process until something else
- * happens to the page.
+ * Emit a WAL XLOG_HEAP2_PRUNE record showing what we did
*/
- if (((PageHeader) page)->pd_prune_xid != prstate.new_prune_xid ||
- PageIsFull(page))
- {
- ((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid;
- PageClearFull(page);
- MarkBufferDirtyHint(buffer, true);
- }
+ if (RelationNeedsWAL(relation))
+ log_heap_prune_and_freeze(relation, buffer, &prstate, presult);
}
END_CRIT_SECTION();
- /* Record number of newly-set-LP_DEAD items for caller */
- presult->nnewlpdead = prstate.ndead;
-
- if (do_freeze)
+ /*
+ * If we froze tuples on the page, the caller can advance relfrozenxid and
+ * relminmxid to the values in pagefrz->FreezePageRelfrozenXid and
+ * pagefrz->FreezePageRelminMxid. Otherwise, it is only safe to advance to
+ * the values in pagefrz->NoFreezePage[RelfrozenXid|RelminMxid]
+ */
+ if (pagefrz)
{
- START_CRIT_SECTION();
+ if (presult->nfrozen > 0)
+ {
+ presult->new_relfrozenxid = pagefrz->FreezePageRelfrozenXid;
+ presult->new_relminmxid = pagefrz->FreezePageRelminMxid;
+ }
+ else
+ {
+ presult->new_relfrozenxid = pagefrz->NoFreezePageRelfrozenXid;
+ presult->new_relminmxid = pagefrz->NoFreezePageRelminMxid;
+ }
+ }
+}
- Assert(presult->nfrozen > 0);
- heap_freeze_prepared_tuples(buffer, prstate.frozen, presult->nfrozen);
+static void
+log_heap_prune_and_freeze(Relation relation, Buffer buffer,
+ PruneState *prstate, PruneFreezeResult *presult)
+{
+ xl_heap_prune xlrec;
+ XLogRecPtr recptr;
- MarkBufferDirty(buffer);
+ xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
+ OffsetNumber offsets[MaxHeapTuplesPerPage];
+ bool do_freeze = presult->nfrozen > 0;
- /* Now WAL-log freezing if necessary */
- if (RelationNeedsWAL(relation))
- {
- xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
- OffsetNumber offsets[MaxHeapTuplesPerPage];
- int nplans;
- xl_heap_freeze_page xlrec;
- XLogRecPtr recptr;
+ xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
+ xlrec.nredirected = prstate->nredirected;
+ xlrec.ndead = prstate->ndead;
+ xlrec.nunused = prstate->nunused;
+ xlrec.nplans = 0;
- /*
- * Prepare deduplicated representation for use in WAL record
- * Destructively sorts tuples array in-place.
- */
- nplans = heap_log_freeze_plan(prstate.frozen, presult->nfrozen, plans, offsets);
+ /*
+ * The snapshotConflictHorizon for the whole record should be the most
+ * conservative of all the horizons calculated for any of the possible
+ * modifications. If this record will prune tuples, any transactions on
+ * the standby older than the youngest xmax of the most recently removed
+ * tuple this record will prune will conflict. If this record will freeze
+ * tuples, any transactions on the standby with xids older than the
+ * youngest tuple this record will freeze will conflict.
+ */
+ if (do_freeze)
+ xlrec.snapshotConflictHorizon = Max(prstate->snapshotConflictHorizon,
+ presult->frz_conflict_horizon);
+ else
+ xlrec.snapshotConflictHorizon = prstate->snapshotConflictHorizon;
- xlrec.snapshotConflictHorizon = presult->frz_conflict_horizon;
- xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.nplans = nplans;
+ /*
+ * Prepare deduplicated representation for use in WAL record Destructively
+ * sorts tuples array in-place.
+ */
+ if (do_freeze)
+ xlrec.nplans = heap_log_freeze_plan(prstate->frozen,
+ presult->nfrozen, plans, offsets);
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, SizeOfHeapFreezePage);
+ XLogBeginInsert();
+ XLogRegisterData((char *) &xlrec, SizeOfHeapPrune);
- /*
- * The freeze plan array and offset array are not actually in the
- * buffer, but pretend that they are. When XLogInsert stores the
- * whole buffer, the arrays need not be stored too.
- */
- XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
- XLogRegisterBufData(0, (char *) plans,
- nplans * sizeof(xl_heap_freeze_plan));
- XLogRegisterBufData(0, (char *) offsets,
- presult->nfrozen * sizeof(OffsetNumber));
+ XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_FREEZE_PAGE);
+ /*
+ * The OffsetNumber arrays are not actually in the buffer, but we pretend
+ * that they are. When XLogInsert stores the whole buffer, the offset
+ * arrays need not be stored too.
+ */
+ if (xlrec.nplans > 0)
+ XLogRegisterBufData(0, (char *) plans,
+ xlrec.nplans * sizeof(xl_heap_freeze_plan));
- PageSetLSN(page, recptr);
- }
+ if (prstate->nredirected > 0)
+ XLogRegisterBufData(0, (char *) prstate->redirected,
+ prstate->nredirected *
+ sizeof(OffsetNumber) * 2);
- END_CRIT_SECTION();
- }
- else if (!pagefrz || !presult->all_frozen || presult->nfrozen > 0)
- {
- /*
- * If we will neither freeze tuples on the page nor set the page all
- * frozen in the visibility map, the page is not all frozen and there
- * will be no newly frozen tuples.
- */
- presult->all_frozen = false;
- presult->nfrozen = 0; /* avoid miscounts in instrumentation */
- }
+ if (prstate->ndead > 0)
+ XLogRegisterBufData(0, (char *) prstate->nowdead,
+ prstate->ndead * sizeof(OffsetNumber));
- /* Caller won't update new_relfrozenxid and new_relminmxid */
- if (!pagefrz)
- return;
+ if (prstate->nunused > 0)
+ XLogRegisterBufData(0, (char *) prstate->nowunused,
+ prstate->nunused * sizeof(OffsetNumber));
+ if (xlrec.nplans > 0)
+ XLogRegisterBufData(0, (char *) offsets,
+ presult->nfrozen * sizeof(OffsetNumber));
- /*
- * If we will freeze tuples on the page or, even if we don't freeze tuples
- * on the page, if we will set the page all-frozen in the visibility map,
- * we can advance relfrozenxid and relminmxid to the values in
- * pagefrz->FreezePageRelfrozenXid and pagefrz->FreezePageRelminMxid.
- */
- if (presult->all_frozen || presult->nfrozen > 0)
- {
- presult->new_relfrozenxid = pagefrz->FreezePageRelfrozenXid;
- presult->new_relminmxid = pagefrz->FreezePageRelminMxid;
- }
- else
- {
- presult->new_relfrozenxid = pagefrz->NoFreezePageRelfrozenXid;
- presult->new_relminmxid = pagefrz->NoFreezePageRelminMxid;
- }
-}
+ recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
+ PageSetLSN(BufferGetPage(buffer), recptr);
+}
/*
* Perform visibility checks for heap pruning.
diff --git a/src/backend/access/rmgrdesc/heapdesc.c b/src/backend/access/rmgrdesc/heapdesc.c
index 36a3d83c8c2..9f0a0341d40 100644
--- a/src/backend/access/rmgrdesc/heapdesc.c
+++ b/src/backend/access/rmgrdesc/heapdesc.c
@@ -179,43 +179,67 @@ heap2_desc(StringInfo buf, XLogReaderState *record)
{
xl_heap_prune *xlrec = (xl_heap_prune *) rec;
- appendStringInfo(buf, "snapshotConflictHorizon: %u, nredirected: %u, ndead: %u, isCatalogRel: %c",
+ appendStringInfo(buf, "snapshotConflictHorizon: %u, isCatalogRel: %c",
xlrec->snapshotConflictHorizon,
- xlrec->nredirected,
- xlrec->ndead,
xlrec->isCatalogRel ? 'T' : 'F');
if (XLogRecHasBlockData(record, 0))
{
- OffsetNumber *end;
OffsetNumber *redirected;
OffsetNumber *nowdead;
OffsetNumber *nowunused;
int nredirected;
+ int ndead;
int nunused;
+ int nplans;
Size datalen;
+ xl_heap_freeze_plan *plans;
+ OffsetNumber *frz_offsets;
- redirected = (OffsetNumber *) XLogRecGetBlockData(record, 0,
- &datalen);
-
+ nplans = xlrec->nplans;
nredirected = xlrec->nredirected;
- end = (OffsetNumber *) ((char *) redirected + datalen);
- nowdead = redirected + (nredirected * 2);
- nowunused = nowdead + xlrec->ndead;
- nunused = (end - nowunused);
- Assert(nunused >= 0);
+ ndead = xlrec->ndead;
+ nunused = xlrec->nunused;
- appendStringInfo(buf, ", nunused: %d", nunused);
-
- appendStringInfoString(buf, ", redirected:");
- array_desc(buf, redirected, sizeof(OffsetNumber) * 2,
- nredirected, &redirect_elem_desc, NULL);
- appendStringInfoString(buf, ", dead:");
- array_desc(buf, nowdead, sizeof(OffsetNumber), xlrec->ndead,
- &offset_elem_desc, NULL);
- appendStringInfoString(buf, ", unused:");
- array_desc(buf, nowunused, sizeof(OffsetNumber), nunused,
- &offset_elem_desc, NULL);
+ plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, &datalen);
+ redirected = (OffsetNumber *) &plans[nplans];
+ nowdead = redirected + (nredirected * 2);
+ nowunused = nowdead + ndead;
+ frz_offsets = nowunused + nunused;
+
+ appendStringInfo(buf, ", nredirected: %u, ndead: %u, nunused: %u, nplans: %u,",
+ nredirected,
+ ndead,
+ nunused,
+ nplans);
+
+ if (nredirected > 0)
+ {
+ appendStringInfoString(buf, ", redirected:");
+ array_desc(buf, redirected, sizeof(OffsetNumber) * 2,
+ nredirected, &redirect_elem_desc, NULL);
+ }
+
+ if (ndead > 0)
+ {
+ appendStringInfoString(buf, ", dead:");
+ array_desc(buf, nowdead, sizeof(OffsetNumber), ndead,
+ &offset_elem_desc, NULL);
+ }
+
+ if (nunused > 0)
+ {
+ appendStringInfoString(buf, ", unused:");
+ array_desc(buf, nowunused, sizeof(OffsetNumber), nunused,
+ &offset_elem_desc, NULL);
+ }
+
+ if (nplans > 0)
+ {
+ appendStringInfoString(buf, ", plans:");
+ array_desc(buf, plans, sizeof(xl_heap_freeze_plan), nplans,
+ &plan_elem_desc, &frz_offsets);
+ }
}
}
else if (info == XLOG_HEAP2_VACUUM)
@@ -235,28 +259,6 @@ heap2_desc(StringInfo buf, XLogReaderState *record)
&offset_elem_desc, NULL);
}
}
- else if (info == XLOG_HEAP2_FREEZE_PAGE)
- {
- xl_heap_freeze_page *xlrec = (xl_heap_freeze_page *) rec;
-
- appendStringInfo(buf, "snapshotConflictHorizon: %u, nplans: %u, isCatalogRel: %c",
- xlrec->snapshotConflictHorizon, xlrec->nplans,
- xlrec->isCatalogRel ? 'T' : 'F');
-
- if (XLogRecHasBlockData(record, 0))
- {
- xl_heap_freeze_plan *plans;
- OffsetNumber *offsets;
-
- plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, NULL);
- offsets = (OffsetNumber *) ((char *) plans +
- (xlrec->nplans *
- sizeof(xl_heap_freeze_plan)));
- appendStringInfoString(buf, ", plans:");
- array_desc(buf, plans, sizeof(xl_heap_freeze_plan), xlrec->nplans,
- &plan_elem_desc, &offsets);
- }
- }
else if (info == XLOG_HEAP2_VISIBLE)
{
xl_heap_visible *xlrec = (xl_heap_visible *) rec;
@@ -361,9 +363,6 @@ heap2_identify(uint8 info)
case XLOG_HEAP2_VACUUM:
id = "VACUUM";
break;
- case XLOG_HEAP2_FREEZE_PAGE:
- id = "FREEZE_PAGE";
- break;
case XLOG_HEAP2_VISIBLE:
id = "VISIBLE";
break;
diff --git a/src/backend/replication/logical/decode.c b/src/backend/replication/logical/decode.c
index e5ab7b78b78..f77051572fd 100644
--- a/src/backend/replication/logical/decode.c
+++ b/src/backend/replication/logical/decode.c
@@ -445,7 +445,6 @@ heap2_decode(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
* Everything else here is just low level physical stuff we're not
* interested in.
*/
- case XLOG_HEAP2_FREEZE_PAGE:
case XLOG_HEAP2_PRUNE:
case XLOG_HEAP2_VACUUM:
case XLOG_HEAP2_VISIBLE:
diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h
index 6488dad5e64..fe4a8ff0620 100644
--- a/src/include/access/heapam_xlog.h
+++ b/src/include/access/heapam_xlog.h
@@ -53,11 +53,10 @@
#define XLOG_HEAP2_REWRITE 0x00
#define XLOG_HEAP2_PRUNE 0x10
#define XLOG_HEAP2_VACUUM 0x20
-#define XLOG_HEAP2_FREEZE_PAGE 0x30
-#define XLOG_HEAP2_VISIBLE 0x40
-#define XLOG_HEAP2_MULTI_INSERT 0x50
-#define XLOG_HEAP2_LOCK_UPDATED 0x60
-#define XLOG_HEAP2_NEW_CID 0x70
+#define XLOG_HEAP2_VISIBLE 0x30
+#define XLOG_HEAP2_MULTI_INSERT 0x40
+#define XLOG_HEAP2_LOCK_UPDATED 0x50
+#define XLOG_HEAP2_NEW_CID 0x60
/*
* xl_heap_insert/xl_heap_multi_insert flag values, 8 bits are available.
@@ -226,28 +225,65 @@ typedef struct xl_heap_update
#define SizeOfHeapUpdate (offsetof(xl_heap_update, new_offnum) + sizeof(OffsetNumber))
+/*
+ * This struct represents a 'freeze plan', which describes how to freeze a
+ * group of one or more heap tuples (appears in xl_heap_prune record)
+ */
+/* 0x01 was XLH_FREEZE_XMIN */
+#define XLH_FREEZE_XVAC 0x02
+#define XLH_INVALID_XVAC 0x04
+
+typedef struct xl_heap_freeze_plan
+{
+ TransactionId xmax;
+ uint16 t_infomask2;
+ uint16 t_infomask;
+ uint8 frzflags;
+
+ /* Length of individual page offset numbers array for this plan */
+ uint16 ntuples;
+} xl_heap_freeze_plan;
+
+/*
+ * As of Postgres 17, XLOG_HEAP2_PRUNE records replace
+ * XLOG_HEAP2_FREEZE_PAGE records.
+ */
+
/*
* This is what we need to know about page pruning (both during VACUUM and
* during opportunistic pruning)
*
* The array of OffsetNumbers following the fixed part of the record contains:
+ * * for each freeze plan: the freeze plan
* * for each redirected item: the item offset, then the offset redirected to
* * for each now-dead item: the item offset
* * for each now-unused item: the item offset
- * The total number of OffsetNumbers is therefore 2*nredirected+ndead+nunused.
- * Note that nunused is not explicitly stored, but may be found by reference
- * to the total record length.
+ * * for each tuple frozen by the freeze plans: the offset of the item corresponding to that tuple
+ * The total number of OffsetNumbers is therefore
+ * (2*nredirected) + ndead + nunused + (sum[plan.ntuples for plan in plans])
*
- * Acquires a full cleanup lock.
+ * Acquires a full cleanup lock if heap_page_prune_execute() must be called
*/
typedef struct xl_heap_prune
{
TransactionId snapshotConflictHorizon;
+ uint16 nplans;
uint16 nredirected;
uint16 ndead;
+ uint16 nunused;
bool isCatalogRel; /* to handle recovery conflict during logical
* decoding on standby */
- /* OFFSET NUMBERS are in the block reference 0 */
+ /*--------------------------------------------------------------------
+ * OFFSET NUMBERS and freeze plans are in the block reference 0 in the
+ * following order:
+ *
+ * * xl_heap_freeze_plan plans[nplans];
+ * * OffsetNumber redirected[2 * nredirected];
+ * * OffsetNumber nowdead[ndead];
+ * * OffsetNumber nowunused[nunused];
+ * * OffsetNumber frz_offsets[...];
+ *--------------------------------------------------------------------
+ */
} xl_heap_prune;
#define SizeOfHeapPrune (offsetof(xl_heap_prune, isCatalogRel) + sizeof(bool))
@@ -315,47 +351,6 @@ typedef struct xl_heap_inplace
#define SizeOfHeapInplace (offsetof(xl_heap_inplace, offnum) + sizeof(OffsetNumber))
-/*
- * This struct represents a 'freeze plan', which describes how to freeze a
- * group of one or more heap tuples (appears in xl_heap_freeze_page record)
- */
-/* 0x01 was XLH_FREEZE_XMIN */
-#define XLH_FREEZE_XVAC 0x02
-#define XLH_INVALID_XVAC 0x04
-
-typedef struct xl_heap_freeze_plan
-{
- TransactionId xmax;
- uint16 t_infomask2;
- uint16 t_infomask;
- uint8 frzflags;
-
- /* Length of individual page offset numbers array for this plan */
- uint16 ntuples;
-} xl_heap_freeze_plan;
-
-/*
- * This is what we need to know about a block being frozen during vacuum
- *
- * Backup block 0's data contains an array of xl_heap_freeze_plan structs
- * (with nplans elements), followed by one or more page offset number arrays.
- * Each such page offset number array corresponds to a single freeze plan
- * (REDO routine freezes corresponding heap tuples using freeze plan).
- */
-typedef struct xl_heap_freeze_page
-{
- TransactionId snapshotConflictHorizon;
- uint16 nplans;
- bool isCatalogRel; /* to handle recovery conflict during logical
- * decoding on standby */
-
- /*
- * In payload of blk 0 : FREEZE PLANS and OFFSET NUMBER ARRAY
- */
-} xl_heap_freeze_page;
-
-#define SizeOfHeapFreezePage (offsetof(xl_heap_freeze_page, isCatalogRel) + sizeof(bool))
-
/*
* This is what we need to know about setting a visibility map bit
*
--
2.40.1
--tez7m2a73jtztiij
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v4-0014-Vacuum-second-pass-emits-XLOG_HEAP2_PRUNE-record.patch"
^ permalink raw reply [nested|flat] 18+ messages in thread
* [PATCH v2 12/17] Merge prune and freeze records
@ 2024-01-07 22:55 Melanie Plageman <[email protected]>
0 siblings, 0 replies; 18+ messages in thread
From: Melanie Plageman @ 2024-01-07 22:55 UTC (permalink / raw)
When there are both tuples to prune and freeze on a page, emit a single,
combined prune record containing the offsets for pruning and the freeze
plans and offsets for freezing. This will reduce the number of WAL
records emitted.
---
src/backend/access/heap/heapam.c | 42 ++++++++++++--
src/backend/access/heap/pruneheap.c | 85 +++++++++++++----------------
src/include/access/heapam_xlog.h | 20 +++++--
3 files changed, 90 insertions(+), 57 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index a3691584c55..a8f35eba3c9 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8803,24 +8803,28 @@ heap_xlog_prune(XLogReaderState *record)
if (action == BLK_NEEDS_REDO)
{
Page page = (Page) BufferGetPage(buffer);
- OffsetNumber *end;
OffsetNumber *redirected;
OffsetNumber *nowdead;
OffsetNumber *nowunused;
int nredirected;
int ndead;
int nunused;
+ int nplans;
Size datalen;
+ xl_heap_freeze_plan *plans;
+ OffsetNumber *frz_offsets;
+ int curoff = 0;
- redirected = (OffsetNumber *) XLogRecGetBlockData(record, 0, &datalen);
-
+ nplans = xlrec->nplans;
nredirected = xlrec->nredirected;
ndead = xlrec->ndead;
- end = (OffsetNumber *) ((char *) redirected + datalen);
+ nunused = xlrec->nunused;
+
+ plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, &datalen);
+ redirected = (OffsetNumber *) &plans[nplans];
nowdead = redirected + (nredirected * 2);
nowunused = nowdead + ndead;
- nunused = (end - nowunused);
- Assert(nunused >= 0);
+ frz_offsets = nowunused + nunused;
/* Update all line pointers per the record, and repair fragmentation */
heap_page_prune_execute(buffer,
@@ -8828,6 +8832,32 @@ heap_xlog_prune(XLogReaderState *record)
nowdead, ndead,
nowunused, nunused);
+ for (int p = 0; p < nplans; p++)
+ {
+ HeapTupleFreeze frz;
+
+ /*
+ * Convert freeze plan representation from WAL record into
+ * per-tuple format used by heap_execute_freeze_tuple
+ */
+ frz.xmax = plans[p].xmax;
+ frz.t_infomask2 = plans[p].t_infomask2;
+ frz.t_infomask = plans[p].t_infomask;
+ frz.frzflags = plans[p].frzflags;
+ frz.offset = InvalidOffsetNumber; /* unused, but be tidy */
+
+ for (int i = 0; i < plans[p].ntuples; i++)
+ {
+ OffsetNumber offset = frz_offsets[curoff++];
+ ItemId lp;
+ HeapTupleHeader tuple;
+
+ lp = PageGetItemId(page, offset);
+ tuple = (HeapTupleHeader) PageGetItem(page, lp);
+ heap_execute_freeze_tuple(tuple, &frz);
+ }
+ }
+
/*
* Note: we don't worry about updating the page's prunability hints.
* At worst this will cause an extra prune cycle to occur soon.
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index ca64c45d8a3..70d35a21e98 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -605,6 +605,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
*/
PageClearFull(page);
+ if (do_freeze)
+ heap_freeze_prepared_tuples(buffer, frozen, presult->nfrozen);
+
MarkBufferDirty(buffer);
/*
@@ -615,10 +618,37 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
xl_heap_prune xlrec;
XLogRecPtr recptr;
+ xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
+ OffsetNumber offsets[MaxHeapTuplesPerPage];
+
xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
xlrec.nredirected = prstate.nredirected;
xlrec.ndead = prstate.ndead;
+ xlrec.nunused = prstate.nunused;
+ xlrec.nplans = 0;
+
+ /*
+ * The snapshotConflictHorizon for the whole record should be the most
+ * conservative of all the horizons calculated for any of the possible
+ * modifications. If this record will prune tuples, any transactions
+ * on the standby older than the youngest xmax of the most recently
+ * removed tuple this record will prune will conflict. If this record
+ * will freeze tuples, any transactions on the standby with xids older
+ * than the youngest tuple this record will freeze will conflict.
+ */
+ if (do_freeze)
+ xlrec.snapshotConflictHorizon = Max(prstate.snapshotConflictHorizon,
+ frz_conflict_horizon);
+ else
+ xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
+
+ /*
+ * Prepare deduplicated representation for use in WAL record
+ * Destructively sorts tuples array in-place.
+ */
+ if (do_freeze)
+ xlrec.nplans = heap_log_freeze_plan(frozen,
+ presult->nfrozen, plans, offsets);
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapPrune);
@@ -630,6 +660,10 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* pretend that they are. When XLogInsert stores the whole buffer,
* the offset arrays need not be stored too.
*/
+ if (xlrec.nplans > 0)
+ XLogRegisterBufData(0, (char *) plans,
+ xlrec.nplans * sizeof(xl_heap_freeze_plan));
+
if (prstate.nredirected > 0)
XLogRegisterBufData(0, (char *) prstate.redirected,
prstate.nredirected *
@@ -643,56 +677,13 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
XLogRegisterBufData(0, (char *) prstate.nowunused,
prstate.nunused * sizeof(OffsetNumber));
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
-
- PageSetLSN(BufferGetPage(buffer), recptr);
- }
-
- if (do_freeze)
- {
- Assert(presult->nfrozen > 0);
-
- heap_freeze_prepared_tuples(buffer, frozen, presult->nfrozen);
-
- MarkBufferDirty(buffer);
-
- /* Now WAL-log freezing if necessary */
- if (RelationNeedsWAL(relation))
- {
- xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
- OffsetNumber offsets[MaxHeapTuplesPerPage];
- int nplans;
- xl_heap_freeze_page xlrec;
- XLogRecPtr recptr;
-
- /*
- * Prepare deduplicated representation for use in WAL record
- * Destructively sorts tuples array in-place.
- */
- nplans = heap_log_freeze_plan(frozen, presult->nfrozen, plans, offsets);
-
- xlrec.snapshotConflictHorizon = frz_conflict_horizon;
- xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.nplans = nplans;
-
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, SizeOfHeapFreezePage);
-
- /*
- * The freeze plan array and offset array are not actually in the
- * buffer, but pretend that they are. When XLogInsert stores the
- * whole buffer, the arrays need not be stored too.
- */
- XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
- XLogRegisterBufData(0, (char *) plans,
- nplans * sizeof(xl_heap_freeze_plan));
+ if (xlrec.nplans > 0)
XLogRegisterBufData(0, (char *) offsets,
presult->nfrozen * sizeof(OffsetNumber));
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_FREEZE_PAGE);
+ recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
- PageSetLSN(page, recptr);
- }
+ PageSetLSN(BufferGetPage(buffer), recptr);
}
END_CRIT_SECTION();
diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h
index 6488dad5e64..22f236bb52a 100644
--- a/src/include/access/heapam_xlog.h
+++ b/src/include/access/heapam_xlog.h
@@ -231,23 +231,35 @@ typedef struct xl_heap_update
* during opportunistic pruning)
*
* The array of OffsetNumbers following the fixed part of the record contains:
+ * * for each freeze plan: the freeze plan
* * for each redirected item: the item offset, then the offset redirected to
* * for each now-dead item: the item offset
* * for each now-unused item: the item offset
- * The total number of OffsetNumbers is therefore 2*nredirected+ndead+nunused.
- * Note that nunused is not explicitly stored, but may be found by reference
- * to the total record length.
+ * * for each tuple frozen by the freeze plans: the offset of the item corresponding to that tuple
+ * The total number of OffsetNumbers is therefore
+ * (2*nredirected) + ndead + nunused + (sum[plan.ntuples for plan in plans])
*
* Acquires a full cleanup lock.
*/
typedef struct xl_heap_prune
{
TransactionId snapshotConflictHorizon;
+ uint16 nplans;
uint16 nredirected;
uint16 ndead;
+ uint16 nunused;
bool isCatalogRel; /* to handle recovery conflict during logical
* decoding on standby */
- /* OFFSET NUMBERS are in the block reference 0 */
+ /*
+ * OFFSET NUMBERS and freeze plans are in the block reference 0 in the
+ * following order:
+ *
+ * * xl_heap_freeze_plan plans[nplans];
+ * * OffsetNumber redirected[2 * nredirected];
+ * * OffsetNumber nowdead[ndead];
+ * * OffsetNumber nowunused[nunused];
+ * * OffsetNumber frz_offsets[...];
+ */
} xl_heap_prune;
#define SizeOfHeapPrune (offsetof(xl_heap_prune, isCatalogRel) + sizeof(bool))
--
2.40.1
--rdqtp5puvxqotfdw
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v2-0013-Set-hastup-in-heap_page_prune.patch"
^ permalink raw reply [nested|flat] 18+ messages in thread
* [PATCH v3 12/17] Merge prune and freeze records
@ 2024-01-07 22:55 Melanie Plageman <[email protected]>
0 siblings, 0 replies; 18+ messages in thread
From: Melanie Plageman @ 2024-01-07 22:55 UTC (permalink / raw)
When there are both tuples to prune and freeze on a page, emit a single,
combined prune record containing the offsets for pruning and the freeze
plans and offsets for freezing. This will reduce the number of WAL
records emitted.
---
src/backend/access/heap/heapam.c | 42 ++++++++++++--
src/backend/access/heap/pruneheap.c | 85 +++++++++++++----------------
src/include/access/heapam_xlog.h | 20 +++++--
3 files changed, 90 insertions(+), 57 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index a3691584c55..a8f35eba3c9 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8803,24 +8803,28 @@ heap_xlog_prune(XLogReaderState *record)
if (action == BLK_NEEDS_REDO)
{
Page page = (Page) BufferGetPage(buffer);
- OffsetNumber *end;
OffsetNumber *redirected;
OffsetNumber *nowdead;
OffsetNumber *nowunused;
int nredirected;
int ndead;
int nunused;
+ int nplans;
Size datalen;
+ xl_heap_freeze_plan *plans;
+ OffsetNumber *frz_offsets;
+ int curoff = 0;
- redirected = (OffsetNumber *) XLogRecGetBlockData(record, 0, &datalen);
-
+ nplans = xlrec->nplans;
nredirected = xlrec->nredirected;
ndead = xlrec->ndead;
- end = (OffsetNumber *) ((char *) redirected + datalen);
+ nunused = xlrec->nunused;
+
+ plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, &datalen);
+ redirected = (OffsetNumber *) &plans[nplans];
nowdead = redirected + (nredirected * 2);
nowunused = nowdead + ndead;
- nunused = (end - nowunused);
- Assert(nunused >= 0);
+ frz_offsets = nowunused + nunused;
/* Update all line pointers per the record, and repair fragmentation */
heap_page_prune_execute(buffer,
@@ -8828,6 +8832,32 @@ heap_xlog_prune(XLogReaderState *record)
nowdead, ndead,
nowunused, nunused);
+ for (int p = 0; p < nplans; p++)
+ {
+ HeapTupleFreeze frz;
+
+ /*
+ * Convert freeze plan representation from WAL record into
+ * per-tuple format used by heap_execute_freeze_tuple
+ */
+ frz.xmax = plans[p].xmax;
+ frz.t_infomask2 = plans[p].t_infomask2;
+ frz.t_infomask = plans[p].t_infomask;
+ frz.frzflags = plans[p].frzflags;
+ frz.offset = InvalidOffsetNumber; /* unused, but be tidy */
+
+ for (int i = 0; i < plans[p].ntuples; i++)
+ {
+ OffsetNumber offset = frz_offsets[curoff++];
+ ItemId lp;
+ HeapTupleHeader tuple;
+
+ lp = PageGetItemId(page, offset);
+ tuple = (HeapTupleHeader) PageGetItem(page, lp);
+ heap_execute_freeze_tuple(tuple, &frz);
+ }
+ }
+
/*
* Note: we don't worry about updating the page's prunability hints.
* At worst this will cause an extra prune cycle to occur soon.
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index d77270ad0d6..994cf75c54e 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -619,6 +619,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
*/
PageClearFull(page);
+ if (do_freeze)
+ heap_freeze_prepared_tuples(buffer, frozen, presult->nfrozen);
+
MarkBufferDirty(buffer);
/*
@@ -629,10 +632,37 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
xl_heap_prune xlrec;
XLogRecPtr recptr;
+ xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
+ OffsetNumber offsets[MaxHeapTuplesPerPage];
+
xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
xlrec.nredirected = prstate.nredirected;
xlrec.ndead = prstate.ndead;
+ xlrec.nunused = prstate.nunused;
+ xlrec.nplans = 0;
+
+ /*
+ * The snapshotConflictHorizon for the whole record should be the most
+ * conservative of all the horizons calculated for any of the possible
+ * modifications. If this record will prune tuples, any transactions
+ * on the standby older than the youngest xmax of the most recently
+ * removed tuple this record will prune will conflict. If this record
+ * will freeze tuples, any transactions on the standby with xids older
+ * than the youngest tuple this record will freeze will conflict.
+ */
+ if (do_freeze)
+ xlrec.snapshotConflictHorizon = Max(prstate.snapshotConflictHorizon,
+ frz_conflict_horizon);
+ else
+ xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
+
+ /*
+ * Prepare deduplicated representation for use in WAL record
+ * Destructively sorts tuples array in-place.
+ */
+ if (do_freeze)
+ xlrec.nplans = heap_log_freeze_plan(frozen,
+ presult->nfrozen, plans, offsets);
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapPrune);
@@ -644,6 +674,10 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* pretend that they are. When XLogInsert stores the whole buffer,
* the offset arrays need not be stored too.
*/
+ if (xlrec.nplans > 0)
+ XLogRegisterBufData(0, (char *) plans,
+ xlrec.nplans * sizeof(xl_heap_freeze_plan));
+
if (prstate.nredirected > 0)
XLogRegisterBufData(0, (char *) prstate.redirected,
prstate.nredirected *
@@ -657,56 +691,13 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
XLogRegisterBufData(0, (char *) prstate.nowunused,
prstate.nunused * sizeof(OffsetNumber));
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
-
- PageSetLSN(BufferGetPage(buffer), recptr);
- }
-
- if (do_freeze)
- {
- Assert(presult->nfrozen > 0);
-
- heap_freeze_prepared_tuples(buffer, frozen, presult->nfrozen);
-
- MarkBufferDirty(buffer);
-
- /* Now WAL-log freezing if necessary */
- if (RelationNeedsWAL(relation))
- {
- xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
- OffsetNumber offsets[MaxHeapTuplesPerPage];
- int nplans;
- xl_heap_freeze_page xlrec;
- XLogRecPtr recptr;
-
- /*
- * Prepare deduplicated representation for use in WAL record
- * Destructively sorts tuples array in-place.
- */
- nplans = heap_log_freeze_plan(frozen, presult->nfrozen, plans, offsets);
-
- xlrec.snapshotConflictHorizon = frz_conflict_horizon;
- xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.nplans = nplans;
-
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, SizeOfHeapFreezePage);
-
- /*
- * The freeze plan array and offset array are not actually in the
- * buffer, but pretend that they are. When XLogInsert stores the
- * whole buffer, the arrays need not be stored too.
- */
- XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
- XLogRegisterBufData(0, (char *) plans,
- nplans * sizeof(xl_heap_freeze_plan));
+ if (xlrec.nplans > 0)
XLogRegisterBufData(0, (char *) offsets,
presult->nfrozen * sizeof(OffsetNumber));
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_FREEZE_PAGE);
+ recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
- PageSetLSN(page, recptr);
- }
+ PageSetLSN(BufferGetPage(buffer), recptr);
}
END_CRIT_SECTION();
diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h
index 6488dad5e64..22f236bb52a 100644
--- a/src/include/access/heapam_xlog.h
+++ b/src/include/access/heapam_xlog.h
@@ -231,23 +231,35 @@ typedef struct xl_heap_update
* during opportunistic pruning)
*
* The array of OffsetNumbers following the fixed part of the record contains:
+ * * for each freeze plan: the freeze plan
* * for each redirected item: the item offset, then the offset redirected to
* * for each now-dead item: the item offset
* * for each now-unused item: the item offset
- * The total number of OffsetNumbers is therefore 2*nredirected+ndead+nunused.
- * Note that nunused is not explicitly stored, but may be found by reference
- * to the total record length.
+ * * for each tuple frozen by the freeze plans: the offset of the item corresponding to that tuple
+ * The total number of OffsetNumbers is therefore
+ * (2*nredirected) + ndead + nunused + (sum[plan.ntuples for plan in plans])
*
* Acquires a full cleanup lock.
*/
typedef struct xl_heap_prune
{
TransactionId snapshotConflictHorizon;
+ uint16 nplans;
uint16 nredirected;
uint16 ndead;
+ uint16 nunused;
bool isCatalogRel; /* to handle recovery conflict during logical
* decoding on standby */
- /* OFFSET NUMBERS are in the block reference 0 */
+ /*
+ * OFFSET NUMBERS and freeze plans are in the block reference 0 in the
+ * following order:
+ *
+ * * xl_heap_freeze_plan plans[nplans];
+ * * OffsetNumber redirected[2 * nredirected];
+ * * OffsetNumber nowdead[ndead];
+ * * OffsetNumber nowunused[nunused];
+ * * OffsetNumber frz_offsets[...];
+ */
} xl_heap_prune;
#define SizeOfHeapPrune (offsetof(xl_heap_prune, isCatalogRel) + sizeof(bool))
--
2.40.1
--racicctn4wry6xe5
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v3-0013-Set-hastup-in-heap_page_prune.patch"
^ permalink raw reply [nested|flat] 18+ messages in thread
* [PATCH v3 12/17] Merge prune and freeze records
@ 2024-01-07 22:55 Melanie Plageman <[email protected]>
0 siblings, 0 replies; 18+ messages in thread
From: Melanie Plageman @ 2024-01-07 22:55 UTC (permalink / raw)
When there are both tuples to prune and freeze on a page, emit a single,
combined prune record containing the offsets for pruning and the freeze
plans and offsets for freezing. This will reduce the number of WAL
records emitted.
---
src/backend/access/heap/heapam.c | 42 ++++++++++++--
src/backend/access/heap/pruneheap.c | 85 +++++++++++++----------------
src/include/access/heapam_xlog.h | 20 +++++--
3 files changed, 90 insertions(+), 57 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index a3691584c55..a8f35eba3c9 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8803,24 +8803,28 @@ heap_xlog_prune(XLogReaderState *record)
if (action == BLK_NEEDS_REDO)
{
Page page = (Page) BufferGetPage(buffer);
- OffsetNumber *end;
OffsetNumber *redirected;
OffsetNumber *nowdead;
OffsetNumber *nowunused;
int nredirected;
int ndead;
int nunused;
+ int nplans;
Size datalen;
+ xl_heap_freeze_plan *plans;
+ OffsetNumber *frz_offsets;
+ int curoff = 0;
- redirected = (OffsetNumber *) XLogRecGetBlockData(record, 0, &datalen);
-
+ nplans = xlrec->nplans;
nredirected = xlrec->nredirected;
ndead = xlrec->ndead;
- end = (OffsetNumber *) ((char *) redirected + datalen);
+ nunused = xlrec->nunused;
+
+ plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, &datalen);
+ redirected = (OffsetNumber *) &plans[nplans];
nowdead = redirected + (nredirected * 2);
nowunused = nowdead + ndead;
- nunused = (end - nowunused);
- Assert(nunused >= 0);
+ frz_offsets = nowunused + nunused;
/* Update all line pointers per the record, and repair fragmentation */
heap_page_prune_execute(buffer,
@@ -8828,6 +8832,32 @@ heap_xlog_prune(XLogReaderState *record)
nowdead, ndead,
nowunused, nunused);
+ for (int p = 0; p < nplans; p++)
+ {
+ HeapTupleFreeze frz;
+
+ /*
+ * Convert freeze plan representation from WAL record into
+ * per-tuple format used by heap_execute_freeze_tuple
+ */
+ frz.xmax = plans[p].xmax;
+ frz.t_infomask2 = plans[p].t_infomask2;
+ frz.t_infomask = plans[p].t_infomask;
+ frz.frzflags = plans[p].frzflags;
+ frz.offset = InvalidOffsetNumber; /* unused, but be tidy */
+
+ for (int i = 0; i < plans[p].ntuples; i++)
+ {
+ OffsetNumber offset = frz_offsets[curoff++];
+ ItemId lp;
+ HeapTupleHeader tuple;
+
+ lp = PageGetItemId(page, offset);
+ tuple = (HeapTupleHeader) PageGetItem(page, lp);
+ heap_execute_freeze_tuple(tuple, &frz);
+ }
+ }
+
/*
* Note: we don't worry about updating the page's prunability hints.
* At worst this will cause an extra prune cycle to occur soon.
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index d77270ad0d6..994cf75c54e 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -619,6 +619,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
*/
PageClearFull(page);
+ if (do_freeze)
+ heap_freeze_prepared_tuples(buffer, frozen, presult->nfrozen);
+
MarkBufferDirty(buffer);
/*
@@ -629,10 +632,37 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
xl_heap_prune xlrec;
XLogRecPtr recptr;
+ xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
+ OffsetNumber offsets[MaxHeapTuplesPerPage];
+
xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
xlrec.nredirected = prstate.nredirected;
xlrec.ndead = prstate.ndead;
+ xlrec.nunused = prstate.nunused;
+ xlrec.nplans = 0;
+
+ /*
+ * The snapshotConflictHorizon for the whole record should be the most
+ * conservative of all the horizons calculated for any of the possible
+ * modifications. If this record will prune tuples, any transactions
+ * on the standby older than the youngest xmax of the most recently
+ * removed tuple this record will prune will conflict. If this record
+ * will freeze tuples, any transactions on the standby with xids older
+ * than the youngest tuple this record will freeze will conflict.
+ */
+ if (do_freeze)
+ xlrec.snapshotConflictHorizon = Max(prstate.snapshotConflictHorizon,
+ frz_conflict_horizon);
+ else
+ xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
+
+ /*
+ * Prepare deduplicated representation for use in WAL record
+ * Destructively sorts tuples array in-place.
+ */
+ if (do_freeze)
+ xlrec.nplans = heap_log_freeze_plan(frozen,
+ presult->nfrozen, plans, offsets);
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapPrune);
@@ -644,6 +674,10 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* pretend that they are. When XLogInsert stores the whole buffer,
* the offset arrays need not be stored too.
*/
+ if (xlrec.nplans > 0)
+ XLogRegisterBufData(0, (char *) plans,
+ xlrec.nplans * sizeof(xl_heap_freeze_plan));
+
if (prstate.nredirected > 0)
XLogRegisterBufData(0, (char *) prstate.redirected,
prstate.nredirected *
@@ -657,56 +691,13 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
XLogRegisterBufData(0, (char *) prstate.nowunused,
prstate.nunused * sizeof(OffsetNumber));
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
-
- PageSetLSN(BufferGetPage(buffer), recptr);
- }
-
- if (do_freeze)
- {
- Assert(presult->nfrozen > 0);
-
- heap_freeze_prepared_tuples(buffer, frozen, presult->nfrozen);
-
- MarkBufferDirty(buffer);
-
- /* Now WAL-log freezing if necessary */
- if (RelationNeedsWAL(relation))
- {
- xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
- OffsetNumber offsets[MaxHeapTuplesPerPage];
- int nplans;
- xl_heap_freeze_page xlrec;
- XLogRecPtr recptr;
-
- /*
- * Prepare deduplicated representation for use in WAL record
- * Destructively sorts tuples array in-place.
- */
- nplans = heap_log_freeze_plan(frozen, presult->nfrozen, plans, offsets);
-
- xlrec.snapshotConflictHorizon = frz_conflict_horizon;
- xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.nplans = nplans;
-
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, SizeOfHeapFreezePage);
-
- /*
- * The freeze plan array and offset array are not actually in the
- * buffer, but pretend that they are. When XLogInsert stores the
- * whole buffer, the arrays need not be stored too.
- */
- XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
- XLogRegisterBufData(0, (char *) plans,
- nplans * sizeof(xl_heap_freeze_plan));
+ if (xlrec.nplans > 0)
XLogRegisterBufData(0, (char *) offsets,
presult->nfrozen * sizeof(OffsetNumber));
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_FREEZE_PAGE);
+ recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
- PageSetLSN(page, recptr);
- }
+ PageSetLSN(BufferGetPage(buffer), recptr);
}
END_CRIT_SECTION();
diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h
index 6488dad5e64..22f236bb52a 100644
--- a/src/include/access/heapam_xlog.h
+++ b/src/include/access/heapam_xlog.h
@@ -231,23 +231,35 @@ typedef struct xl_heap_update
* during opportunistic pruning)
*
* The array of OffsetNumbers following the fixed part of the record contains:
+ * * for each freeze plan: the freeze plan
* * for each redirected item: the item offset, then the offset redirected to
* * for each now-dead item: the item offset
* * for each now-unused item: the item offset
- * The total number of OffsetNumbers is therefore 2*nredirected+ndead+nunused.
- * Note that nunused is not explicitly stored, but may be found by reference
- * to the total record length.
+ * * for each tuple frozen by the freeze plans: the offset of the item corresponding to that tuple
+ * The total number of OffsetNumbers is therefore
+ * (2*nredirected) + ndead + nunused + (sum[plan.ntuples for plan in plans])
*
* Acquires a full cleanup lock.
*/
typedef struct xl_heap_prune
{
TransactionId snapshotConflictHorizon;
+ uint16 nplans;
uint16 nredirected;
uint16 ndead;
+ uint16 nunused;
bool isCatalogRel; /* to handle recovery conflict during logical
* decoding on standby */
- /* OFFSET NUMBERS are in the block reference 0 */
+ /*
+ * OFFSET NUMBERS and freeze plans are in the block reference 0 in the
+ * following order:
+ *
+ * * xl_heap_freeze_plan plans[nplans];
+ * * OffsetNumber redirected[2 * nredirected];
+ * * OffsetNumber nowdead[ndead];
+ * * OffsetNumber nowunused[nunused];
+ * * OffsetNumber frz_offsets[...];
+ */
} xl_heap_prune;
#define SizeOfHeapPrune (offsetof(xl_heap_prune, isCatalogRel) + sizeof(bool))
--
2.40.1
--racicctn4wry6xe5
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v3-0013-Set-hastup-in-heap_page_prune.patch"
^ permalink raw reply [nested|flat] 18+ messages in thread
* [PATCH v2 12/17] Merge prune and freeze records
@ 2024-01-07 22:55 Melanie Plageman <[email protected]>
0 siblings, 0 replies; 18+ messages in thread
From: Melanie Plageman @ 2024-01-07 22:55 UTC (permalink / raw)
When there are both tuples to prune and freeze on a page, emit a single,
combined prune record containing the offsets for pruning and the freeze
plans and offsets for freezing. This will reduce the number of WAL
records emitted.
---
src/backend/access/heap/heapam.c | 42 ++++++++++++--
src/backend/access/heap/pruneheap.c | 85 +++++++++++++----------------
src/include/access/heapam_xlog.h | 20 +++++--
3 files changed, 90 insertions(+), 57 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index a3691584c55..a8f35eba3c9 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8803,24 +8803,28 @@ heap_xlog_prune(XLogReaderState *record)
if (action == BLK_NEEDS_REDO)
{
Page page = (Page) BufferGetPage(buffer);
- OffsetNumber *end;
OffsetNumber *redirected;
OffsetNumber *nowdead;
OffsetNumber *nowunused;
int nredirected;
int ndead;
int nunused;
+ int nplans;
Size datalen;
+ xl_heap_freeze_plan *plans;
+ OffsetNumber *frz_offsets;
+ int curoff = 0;
- redirected = (OffsetNumber *) XLogRecGetBlockData(record, 0, &datalen);
-
+ nplans = xlrec->nplans;
nredirected = xlrec->nredirected;
ndead = xlrec->ndead;
- end = (OffsetNumber *) ((char *) redirected + datalen);
+ nunused = xlrec->nunused;
+
+ plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, &datalen);
+ redirected = (OffsetNumber *) &plans[nplans];
nowdead = redirected + (nredirected * 2);
nowunused = nowdead + ndead;
- nunused = (end - nowunused);
- Assert(nunused >= 0);
+ frz_offsets = nowunused + nunused;
/* Update all line pointers per the record, and repair fragmentation */
heap_page_prune_execute(buffer,
@@ -8828,6 +8832,32 @@ heap_xlog_prune(XLogReaderState *record)
nowdead, ndead,
nowunused, nunused);
+ for (int p = 0; p < nplans; p++)
+ {
+ HeapTupleFreeze frz;
+
+ /*
+ * Convert freeze plan representation from WAL record into
+ * per-tuple format used by heap_execute_freeze_tuple
+ */
+ frz.xmax = plans[p].xmax;
+ frz.t_infomask2 = plans[p].t_infomask2;
+ frz.t_infomask = plans[p].t_infomask;
+ frz.frzflags = plans[p].frzflags;
+ frz.offset = InvalidOffsetNumber; /* unused, but be tidy */
+
+ for (int i = 0; i < plans[p].ntuples; i++)
+ {
+ OffsetNumber offset = frz_offsets[curoff++];
+ ItemId lp;
+ HeapTupleHeader tuple;
+
+ lp = PageGetItemId(page, offset);
+ tuple = (HeapTupleHeader) PageGetItem(page, lp);
+ heap_execute_freeze_tuple(tuple, &frz);
+ }
+ }
+
/*
* Note: we don't worry about updating the page's prunability hints.
* At worst this will cause an extra prune cycle to occur soon.
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index ca64c45d8a3..70d35a21e98 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -605,6 +605,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
*/
PageClearFull(page);
+ if (do_freeze)
+ heap_freeze_prepared_tuples(buffer, frozen, presult->nfrozen);
+
MarkBufferDirty(buffer);
/*
@@ -615,10 +618,37 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
xl_heap_prune xlrec;
XLogRecPtr recptr;
+ xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
+ OffsetNumber offsets[MaxHeapTuplesPerPage];
+
xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
xlrec.nredirected = prstate.nredirected;
xlrec.ndead = prstate.ndead;
+ xlrec.nunused = prstate.nunused;
+ xlrec.nplans = 0;
+
+ /*
+ * The snapshotConflictHorizon for the whole record should be the most
+ * conservative of all the horizons calculated for any of the possible
+ * modifications. If this record will prune tuples, any transactions
+ * on the standby older than the youngest xmax of the most recently
+ * removed tuple this record will prune will conflict. If this record
+ * will freeze tuples, any transactions on the standby with xids older
+ * than the youngest tuple this record will freeze will conflict.
+ */
+ if (do_freeze)
+ xlrec.snapshotConflictHorizon = Max(prstate.snapshotConflictHorizon,
+ frz_conflict_horizon);
+ else
+ xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
+
+ /*
+ * Prepare deduplicated representation for use in WAL record
+ * Destructively sorts tuples array in-place.
+ */
+ if (do_freeze)
+ xlrec.nplans = heap_log_freeze_plan(frozen,
+ presult->nfrozen, plans, offsets);
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapPrune);
@@ -630,6 +660,10 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* pretend that they are. When XLogInsert stores the whole buffer,
* the offset arrays need not be stored too.
*/
+ if (xlrec.nplans > 0)
+ XLogRegisterBufData(0, (char *) plans,
+ xlrec.nplans * sizeof(xl_heap_freeze_plan));
+
if (prstate.nredirected > 0)
XLogRegisterBufData(0, (char *) prstate.redirected,
prstate.nredirected *
@@ -643,56 +677,13 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
XLogRegisterBufData(0, (char *) prstate.nowunused,
prstate.nunused * sizeof(OffsetNumber));
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
-
- PageSetLSN(BufferGetPage(buffer), recptr);
- }
-
- if (do_freeze)
- {
- Assert(presult->nfrozen > 0);
-
- heap_freeze_prepared_tuples(buffer, frozen, presult->nfrozen);
-
- MarkBufferDirty(buffer);
-
- /* Now WAL-log freezing if necessary */
- if (RelationNeedsWAL(relation))
- {
- xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
- OffsetNumber offsets[MaxHeapTuplesPerPage];
- int nplans;
- xl_heap_freeze_page xlrec;
- XLogRecPtr recptr;
-
- /*
- * Prepare deduplicated representation for use in WAL record
- * Destructively sorts tuples array in-place.
- */
- nplans = heap_log_freeze_plan(frozen, presult->nfrozen, plans, offsets);
-
- xlrec.snapshotConflictHorizon = frz_conflict_horizon;
- xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.nplans = nplans;
-
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, SizeOfHeapFreezePage);
-
- /*
- * The freeze plan array and offset array are not actually in the
- * buffer, but pretend that they are. When XLogInsert stores the
- * whole buffer, the arrays need not be stored too.
- */
- XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
- XLogRegisterBufData(0, (char *) plans,
- nplans * sizeof(xl_heap_freeze_plan));
+ if (xlrec.nplans > 0)
XLogRegisterBufData(0, (char *) offsets,
presult->nfrozen * sizeof(OffsetNumber));
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_FREEZE_PAGE);
+ recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
- PageSetLSN(page, recptr);
- }
+ PageSetLSN(BufferGetPage(buffer), recptr);
}
END_CRIT_SECTION();
diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h
index 6488dad5e64..22f236bb52a 100644
--- a/src/include/access/heapam_xlog.h
+++ b/src/include/access/heapam_xlog.h
@@ -231,23 +231,35 @@ typedef struct xl_heap_update
* during opportunistic pruning)
*
* The array of OffsetNumbers following the fixed part of the record contains:
+ * * for each freeze plan: the freeze plan
* * for each redirected item: the item offset, then the offset redirected to
* * for each now-dead item: the item offset
* * for each now-unused item: the item offset
- * The total number of OffsetNumbers is therefore 2*nredirected+ndead+nunused.
- * Note that nunused is not explicitly stored, but may be found by reference
- * to the total record length.
+ * * for each tuple frozen by the freeze plans: the offset of the item corresponding to that tuple
+ * The total number of OffsetNumbers is therefore
+ * (2*nredirected) + ndead + nunused + (sum[plan.ntuples for plan in plans])
*
* Acquires a full cleanup lock.
*/
typedef struct xl_heap_prune
{
TransactionId snapshotConflictHorizon;
+ uint16 nplans;
uint16 nredirected;
uint16 ndead;
+ uint16 nunused;
bool isCatalogRel; /* to handle recovery conflict during logical
* decoding on standby */
- /* OFFSET NUMBERS are in the block reference 0 */
+ /*
+ * OFFSET NUMBERS and freeze plans are in the block reference 0 in the
+ * following order:
+ *
+ * * xl_heap_freeze_plan plans[nplans];
+ * * OffsetNumber redirected[2 * nredirected];
+ * * OffsetNumber nowdead[ndead];
+ * * OffsetNumber nowunused[nunused];
+ * * OffsetNumber frz_offsets[...];
+ */
} xl_heap_prune;
#define SizeOfHeapPrune (offsetof(xl_heap_prune, isCatalogRel) + sizeof(bool))
--
2.40.1
--rdqtp5puvxqotfdw
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v2-0013-Set-hastup-in-heap_page_prune.patch"
^ permalink raw reply [nested|flat] 18+ messages in thread
* [PATCH v2 12/17] Merge prune and freeze records
@ 2024-01-07 22:55 Melanie Plageman <[email protected]>
0 siblings, 0 replies; 18+ messages in thread
From: Melanie Plageman @ 2024-01-07 22:55 UTC (permalink / raw)
When there are both tuples to prune and freeze on a page, emit a single,
combined prune record containing the offsets for pruning and the freeze
plans and offsets for freezing. This will reduce the number of WAL
records emitted.
---
src/backend/access/heap/heapam.c | 42 ++++++++++++--
src/backend/access/heap/pruneheap.c | 85 +++++++++++++----------------
src/include/access/heapam_xlog.h | 20 +++++--
3 files changed, 90 insertions(+), 57 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index a3691584c55..a8f35eba3c9 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -8803,24 +8803,28 @@ heap_xlog_prune(XLogReaderState *record)
if (action == BLK_NEEDS_REDO)
{
Page page = (Page) BufferGetPage(buffer);
- OffsetNumber *end;
OffsetNumber *redirected;
OffsetNumber *nowdead;
OffsetNumber *nowunused;
int nredirected;
int ndead;
int nunused;
+ int nplans;
Size datalen;
+ xl_heap_freeze_plan *plans;
+ OffsetNumber *frz_offsets;
+ int curoff = 0;
- redirected = (OffsetNumber *) XLogRecGetBlockData(record, 0, &datalen);
-
+ nplans = xlrec->nplans;
nredirected = xlrec->nredirected;
ndead = xlrec->ndead;
- end = (OffsetNumber *) ((char *) redirected + datalen);
+ nunused = xlrec->nunused;
+
+ plans = (xl_heap_freeze_plan *) XLogRecGetBlockData(record, 0, &datalen);
+ redirected = (OffsetNumber *) &plans[nplans];
nowdead = redirected + (nredirected * 2);
nowunused = nowdead + ndead;
- nunused = (end - nowunused);
- Assert(nunused >= 0);
+ frz_offsets = nowunused + nunused;
/* Update all line pointers per the record, and repair fragmentation */
heap_page_prune_execute(buffer,
@@ -8828,6 +8832,32 @@ heap_xlog_prune(XLogReaderState *record)
nowdead, ndead,
nowunused, nunused);
+ for (int p = 0; p < nplans; p++)
+ {
+ HeapTupleFreeze frz;
+
+ /*
+ * Convert freeze plan representation from WAL record into
+ * per-tuple format used by heap_execute_freeze_tuple
+ */
+ frz.xmax = plans[p].xmax;
+ frz.t_infomask2 = plans[p].t_infomask2;
+ frz.t_infomask = plans[p].t_infomask;
+ frz.frzflags = plans[p].frzflags;
+ frz.offset = InvalidOffsetNumber; /* unused, but be tidy */
+
+ for (int i = 0; i < plans[p].ntuples; i++)
+ {
+ OffsetNumber offset = frz_offsets[curoff++];
+ ItemId lp;
+ HeapTupleHeader tuple;
+
+ lp = PageGetItemId(page, offset);
+ tuple = (HeapTupleHeader) PageGetItem(page, lp);
+ heap_execute_freeze_tuple(tuple, &frz);
+ }
+ }
+
/*
* Note: we don't worry about updating the page's prunability hints.
* At worst this will cause an extra prune cycle to occur soon.
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index ca64c45d8a3..70d35a21e98 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -605,6 +605,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
*/
PageClearFull(page);
+ if (do_freeze)
+ heap_freeze_prepared_tuples(buffer, frozen, presult->nfrozen);
+
MarkBufferDirty(buffer);
/*
@@ -615,10 +618,37 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
xl_heap_prune xlrec;
XLogRecPtr recptr;
+ xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
+ OffsetNumber offsets[MaxHeapTuplesPerPage];
+
xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
xlrec.nredirected = prstate.nredirected;
xlrec.ndead = prstate.ndead;
+ xlrec.nunused = prstate.nunused;
+ xlrec.nplans = 0;
+
+ /*
+ * The snapshotConflictHorizon for the whole record should be the most
+ * conservative of all the horizons calculated for any of the possible
+ * modifications. If this record will prune tuples, any transactions
+ * on the standby older than the youngest xmax of the most recently
+ * removed tuple this record will prune will conflict. If this record
+ * will freeze tuples, any transactions on the standby with xids older
+ * than the youngest tuple this record will freeze will conflict.
+ */
+ if (do_freeze)
+ xlrec.snapshotConflictHorizon = Max(prstate.snapshotConflictHorizon,
+ frz_conflict_horizon);
+ else
+ xlrec.snapshotConflictHorizon = prstate.snapshotConflictHorizon;
+
+ /*
+ * Prepare deduplicated representation for use in WAL record
+ * Destructively sorts tuples array in-place.
+ */
+ if (do_freeze)
+ xlrec.nplans = heap_log_freeze_plan(frozen,
+ presult->nfrozen, plans, offsets);
XLogBeginInsert();
XLogRegisterData((char *) &xlrec, SizeOfHeapPrune);
@@ -630,6 +660,10 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* pretend that they are. When XLogInsert stores the whole buffer,
* the offset arrays need not be stored too.
*/
+ if (xlrec.nplans > 0)
+ XLogRegisterBufData(0, (char *) plans,
+ xlrec.nplans * sizeof(xl_heap_freeze_plan));
+
if (prstate.nredirected > 0)
XLogRegisterBufData(0, (char *) prstate.redirected,
prstate.nredirected *
@@ -643,56 +677,13 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
XLogRegisterBufData(0, (char *) prstate.nowunused,
prstate.nunused * sizeof(OffsetNumber));
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
-
- PageSetLSN(BufferGetPage(buffer), recptr);
- }
-
- if (do_freeze)
- {
- Assert(presult->nfrozen > 0);
-
- heap_freeze_prepared_tuples(buffer, frozen, presult->nfrozen);
-
- MarkBufferDirty(buffer);
-
- /* Now WAL-log freezing if necessary */
- if (RelationNeedsWAL(relation))
- {
- xl_heap_freeze_plan plans[MaxHeapTuplesPerPage];
- OffsetNumber offsets[MaxHeapTuplesPerPage];
- int nplans;
- xl_heap_freeze_page xlrec;
- XLogRecPtr recptr;
-
- /*
- * Prepare deduplicated representation for use in WAL record
- * Destructively sorts tuples array in-place.
- */
- nplans = heap_log_freeze_plan(frozen, presult->nfrozen, plans, offsets);
-
- xlrec.snapshotConflictHorizon = frz_conflict_horizon;
- xlrec.isCatalogRel = RelationIsAccessibleInLogicalDecoding(relation);
- xlrec.nplans = nplans;
-
- XLogBeginInsert();
- XLogRegisterData((char *) &xlrec, SizeOfHeapFreezePage);
-
- /*
- * The freeze plan array and offset array are not actually in the
- * buffer, but pretend that they are. When XLogInsert stores the
- * whole buffer, the arrays need not be stored too.
- */
- XLogRegisterBuffer(0, buffer, REGBUF_STANDARD);
- XLogRegisterBufData(0, (char *) plans,
- nplans * sizeof(xl_heap_freeze_plan));
+ if (xlrec.nplans > 0)
XLogRegisterBufData(0, (char *) offsets,
presult->nfrozen * sizeof(OffsetNumber));
- recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_FREEZE_PAGE);
+ recptr = XLogInsert(RM_HEAP2_ID, XLOG_HEAP2_PRUNE);
- PageSetLSN(page, recptr);
- }
+ PageSetLSN(BufferGetPage(buffer), recptr);
}
END_CRIT_SECTION();
diff --git a/src/include/access/heapam_xlog.h b/src/include/access/heapam_xlog.h
index 6488dad5e64..22f236bb52a 100644
--- a/src/include/access/heapam_xlog.h
+++ b/src/include/access/heapam_xlog.h
@@ -231,23 +231,35 @@ typedef struct xl_heap_update
* during opportunistic pruning)
*
* The array of OffsetNumbers following the fixed part of the record contains:
+ * * for each freeze plan: the freeze plan
* * for each redirected item: the item offset, then the offset redirected to
* * for each now-dead item: the item offset
* * for each now-unused item: the item offset
- * The total number of OffsetNumbers is therefore 2*nredirected+ndead+nunused.
- * Note that nunused is not explicitly stored, but may be found by reference
- * to the total record length.
+ * * for each tuple frozen by the freeze plans: the offset of the item corresponding to that tuple
+ * The total number of OffsetNumbers is therefore
+ * (2*nredirected) + ndead + nunused + (sum[plan.ntuples for plan in plans])
*
* Acquires a full cleanup lock.
*/
typedef struct xl_heap_prune
{
TransactionId snapshotConflictHorizon;
+ uint16 nplans;
uint16 nredirected;
uint16 ndead;
+ uint16 nunused;
bool isCatalogRel; /* to handle recovery conflict during logical
* decoding on standby */
- /* OFFSET NUMBERS are in the block reference 0 */
+ /*
+ * OFFSET NUMBERS and freeze plans are in the block reference 0 in the
+ * following order:
+ *
+ * * xl_heap_freeze_plan plans[nplans];
+ * * OffsetNumber redirected[2 * nredirected];
+ * * OffsetNumber nowdead[ndead];
+ * * OffsetNumber nowunused[nunused];
+ * * OffsetNumber frz_offsets[...];
+ */
} xl_heap_prune;
#define SizeOfHeapPrune (offsetof(xl_heap_prune, isCatalogRel) + sizeof(bool))
--
2.40.1
--rdqtp5puvxqotfdw
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v2-0013-Set-hastup-in-heap_page_prune.patch"
^ permalink raw reply [nested|flat] 18+ messages in thread
* [PATCH v9 12/21] Merge prune and freeze records
@ 2024-03-26 13:37 Melanie Plageman <[email protected]>
0 siblings, 0 replies; 18+ messages in thread
From: Melanie Plageman @ 2024-03-26 13:37 UTC (permalink / raw)
When both pruning and freezing is done, this means a single, combined
WAL record is emitted for both operations. This will reduce the number
of WAL records emitted.
When there are only tuples to freeze present, we can avoid taking a full
cleanup lock when replaying the record.
---
src/backend/access/heap/heapam.c | 2 -
src/backend/access/heap/pruneheap.c | 215 +++++++++++++++-------------
2 files changed, 114 insertions(+), 103 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 41c1c7d286f..aefc0be0dd3 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -6836,8 +6836,6 @@ heap_freeze_prepared_tuples(Buffer buffer, HeapTupleFreeze *tuples, int ntuples)
htup = (HeapTupleHeader) PageGetItem(page, itemid);
heap_execute_freeze_tuple(htup, frz);
}
-
- MarkBufferDirty(buffer);
}
/*
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index 5d8c881c2fc..6085fd1a8f9 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -249,9 +249,8 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
bool do_freeze;
bool all_visible_except_removable;
bool do_prune;
- bool whole_page_freezable;
+ bool do_hint;
bool hint_bit_fpi;
- bool prune_fpi = false;
int64 fpi_before = pgWalUsage.wal_fpi;
/*
@@ -464,10 +463,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
/*
* If checksums are enabled, heap_prune_satisfies_vacuum() may have caused
- * an FPI to be emitted. Then reset fpi_before for no prune case.
+ * an FPI to be emitted.
*/
hint_bit_fpi = fpi_before != pgWalUsage.wal_fpi;
- fpi_before = pgWalUsage.wal_fpi;
/*
* For vacuum, if the whole page will become frozen, we consider
@@ -517,16 +515,16 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
prstate.ndead > 0 ||
prstate.nunused > 0;
+ /* Record number of newly-set-LP_DEAD items for caller */
+ presult->nnewlpdead = prstate.ndead;
+
/*
- * Only incur overhead of checking if we will do an FPI if we might use
- * the information.
+ * Even if we don't prune anything, if we found a new value for the
+ * pd_prune_xid field or the page was marked full, we will update the hint
+ * bit.
*/
- if (do_prune && pagefrz)
- prune_fpi = XLogCheckBufferNeedsBackup(buffer);
-
- /* Is the whole page freezable? And is there something to freeze */
- whole_page_freezable = all_visible_except_removable &&
- presult->all_frozen;
+ do_hint = ((PageHeader) page)->pd_prune_xid != prstate.new_prune_xid ||
+ PageIsFull(page);
/*
* Freeze the page when heap_prepare_freeze_tuple indicates that at least
@@ -539,46 +537,57 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* opportunistic freeze heuristic must be improved; however, for now, try
* to approximate it.
*/
- do_freeze = pagefrz &&
- (pagefrz->freeze_required ||
- (whole_page_freezable && presult->nfrozen > 0 && (prune_fpi || hint_bit_fpi)));
- if (do_freeze)
+ do_freeze = false;
+ if (pagefrz)
{
- heap_pre_freeze_checks(buffer, prstate.frozen, presult->nfrozen);
+ /* Is the whole page freezable? And is there something to freeze? */
+ bool whole_page_freezable = all_visible_except_removable &&
+ presult->all_frozen;
- /*
- * We can use the visibility_cutoff_xid as our cutoff for conflicts
- * when the whole page is eligible to become all-frozen in the VM once
- * we're done with it. Otherwise we generate a conservative cutoff by
- * stepping back from OldestXmin. This avoids false conflicts when
- * hot_standby_feedback is in use.
- */
- if (all_visible_except_removable && presult->all_frozen)
- frz_conflict_horizon = visibility_cutoff_xid;
- else
+ if (pagefrz->freeze_required)
+ do_freeze = true;
+ else if (whole_page_freezable && presult->nfrozen > 0)
{
- /* Avoids false conflicts when hot_standby_feedback in use */
- frz_conflict_horizon = pagefrz->cutoffs->OldestXmin;
- TransactionIdRetreat(frz_conflict_horizon);
+ /*
+ * Freezing would make the page all-frozen. In this case, we will
+ * freeze if we have already emitted an FPI or will do so anyway.
+ * Be sure only to incur the overhead of checking if we will do an
+ * FPI if we may use that information.
+ */
+ if (hint_bit_fpi ||
+ ((do_prune || do_hint) && XLogCheckBufferNeedsBackup(buffer)))
+ {
+ do_freeze = true;
+ }
}
}
- /* Any error while applying the changes is critical */
- START_CRIT_SECTION();
+ /*
+ * Validate the tuples we are considering freezing. We do this even if
+ * pruning and hint bit setting have not emitted an FPI so far because we
+ * still may emit an FPI while setting the page hint bit later. But we
+ * want to avoid doing the pre-freeze checks in a critical section.
+ */
+ if (do_freeze)
+ heap_pre_freeze_checks(buffer, prstate.frozen, presult->nfrozen);
- /* Have we found any prunable items? */
- if (do_prune)
+ if (!do_freeze && (!pagefrz || !presult->all_frozen || presult->nfrozen > 0))
{
/*
- * Apply the planned item changes, then repair page fragmentation, and
- * update the page's hint bit about whether it has free line pointers.
+ * If we will neither freeze tuples on the page nor set the page all
+ * frozen in the visibility map, the page is not all-frozen and there
+ * will be no newly frozen tuples.
*/
- heap_page_prune_execute(buffer, false,
- prstate.redirected, prstate.nredirected,
- prstate.nowdead, prstate.ndead,
- prstate.nowunused, prstate.nunused);
+ presult->all_frozen = false;
+ presult->nfrozen = 0; /* avoid miscounts in instrumentation */
+ }
+
+ /* Any error while applying the changes is critical */
+ START_CRIT_SECTION();
+ if (do_hint)
+ {
/*
* Update the page's pd_prune_xid field to either zero, or the lowest
* XID of any soon-prunable tuple.
@@ -586,12 +595,52 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid;
/*
- * Also clear the "page is full" flag, since there's no point in
- * repeating the prune/defrag process until something else happens to
- * the page.
+ * Clear the "page is full" flag if it is set since there's no point
+ * in repeating the prune/defrag process until something else happens
+ * to the page.
*/
PageClearFull(page);
+ /*
+ * We only needed to update pd_prune_xid and clear the page-is-full
+ * hint bit, this is a non-WAL-logged hint. If we will also freeze or
+ * prune the page, we will mark the buffer dirty below.
+ */
+ if (!do_freeze && !do_prune)
+ MarkBufferDirtyHint(buffer, true);
+ }
+
+ if (do_prune || do_freeze)
+ {
+ /* Apply the planned item changes, then repair page fragmentation. */
+ if (do_prune)
+ {
+ heap_page_prune_execute(buffer, false,
+ prstate.redirected, prstate.nredirected,
+ prstate.nowdead, prstate.ndead,
+ prstate.nowunused, prstate.nunused);
+ }
+
+ if (do_freeze)
+ {
+ /*
+ * We can use the visibility_cutoff_xid as our cutoff for
+ * conflicts when the whole page is eligible to become all-frozen
+ * in the VM once we're done with it. Otherwise we generate a
+ * conservative cutoff by stepping back from OldestXmin. This
+ * avoids false conflicts when hot_standby_feedback is in use.
+ */
+ if (all_visible_except_removable && presult->all_frozen)
+ frz_conflict_horizon = visibility_cutoff_xid;
+ else
+ {
+ /* Avoids false conflicts when hot_standby_feedback in use */
+ frz_conflict_horizon = pagefrz->cutoffs->OldestXmin;
+ TransactionIdRetreat(frz_conflict_horizon);
+ }
+ heap_freeze_prepared_tuples(buffer, prstate.frozen, presult->nfrozen);
+ }
+
MarkBufferDirty(buffer);
/*
@@ -599,72 +648,35 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
*/
if (RelationNeedsWAL(relation))
{
+ /*
+ * The snapshotConflictHorizon for the whole record should be the
+ * most conservative of all the horizons calculated for any of the
+ * possible modifications. If this record will prune tuples, any
+ * transactions on the standby older than the youngest xmax of the
+ * most recently removed tuple this record will prune will
+ * conflict. If this record will freeze tuples, any transactions
+ * on the standby with xids older than the youngest tuple this
+ * record will freeze will conflict.
+ */
+ TransactionId conflict_xid;
+
+ if (TransactionIdFollows(frz_conflict_horizon, prstate.latest_xid_removed))
+ conflict_xid = frz_conflict_horizon;
+ else
+ conflict_xid = prstate.latest_xid_removed;
+
log_heap_prune_and_freeze(relation, buffer,
- prstate.latest_xid_removed,
+ conflict_xid,
true, reason,
- NULL, 0,
+ prstate.frozen, presult->nfrozen,
prstate.redirected, prstate.nredirected,
prstate.nowdead, prstate.ndead,
prstate.nowunused, prstate.nunused);
}
}
- else
- {
- /*
- * If we didn't prune anything, but have found a new value for the
- * pd_prune_xid field, update it and mark the buffer dirty. This is
- * treated as a non-WAL-logged hint.
- *
- * Also clear the "page is full" flag if it is set, since there's no
- * point in repeating the prune/defrag process until something else
- * happens to the page.
- */
- if (((PageHeader) page)->pd_prune_xid != prstate.new_prune_xid ||
- PageIsFull(page))
- {
- ((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid;
- PageClearFull(page);
- MarkBufferDirtyHint(buffer, true);
- }
- }
END_CRIT_SECTION();
- /* Record number of newly-set-LP_DEAD items for caller */
- presult->nnewlpdead = prstate.ndead;
-
- if (do_freeze)
- {
- START_CRIT_SECTION();
-
- Assert(presult->nfrozen > 0);
-
- heap_freeze_prepared_tuples(buffer, prstate.frozen, presult->nfrozen);
-
- MarkBufferDirty(buffer);
-
- /* Now WAL-log freezing if necessary */
- if (RelationNeedsWAL(relation))
- log_heap_prune_and_freeze(relation, buffer,
- frz_conflict_horizon, false, reason,
- prstate.frozen, presult->nfrozen,
- NULL, 0, /* redirected */
- NULL, 0, /* dead */
- NULL, 0); /* unused */
-
- END_CRIT_SECTION();
- }
- else if (!pagefrz || !presult->all_frozen || presult->nfrozen > 0)
- {
- /*
- * If we will neither freeze tuples on the page nor set the page all
- * frozen in the visibility map, the page is not all frozen and there
- * will be no newly frozen tuples.
- */
- presult->all_frozen = false;
- presult->nfrozen = 0; /* avoid miscounts in instrumentation */
- }
-
/*
* For callers planning to update the visibility map, the conflict horizon
* for that record must be the newest xmin on the page. However, if the
@@ -681,9 +693,10 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* tuples on the page, if we will set the page all-frozen in the
* visibility map, we can advance relfrozenxid and relminmxid to the
* values in pagefrz->FreezePageRelfrozenXid and
- * pagefrz->FreezePageRelminMxid.
+ * pagefrz->FreezePageRelminMxid. MFIXME: which one should be pick if
+ * presult->nfrozen == 0 and presult->all_frozen = True.
*/
- if (presult->all_frozen || presult->nfrozen > 0)
+ if (presult->nfrozen > 0)
{
presult->new_relfrozenxid = pagefrz->FreezePageRelfrozenXid;
presult->new_relminmxid = pagefrz->FreezePageRelminMxid;
--
2.40.1
--caj67xgx3lukmr5f
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v9-0013-Set-hastup-in-heap_page_prune.patch"
^ permalink raw reply [nested|flat] 18+ messages in thread
* [PATCH v7 12/16] Merge prune and freeze records
@ 2024-03-26 13:37 Melanie Plageman <[email protected]>
0 siblings, 0 replies; 18+ messages in thread
From: Melanie Plageman @ 2024-03-26 13:37 UTC (permalink / raw)
When both pruning and freezing is done, this means a single, combined
WAL record is emitted for both operations. This will reduce the number
of WAL records emitted.
When there are only tuples to freeze present, we can avoid taking a full
cleanup lock when replaying the record.
---
src/backend/access/heap/heapam.c | 2 -
src/backend/access/heap/pruneheap.c | 215 +++++++++++++++-------------
2 files changed, 114 insertions(+), 103 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 1c1785994b1..5d8f183085d 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -6731,8 +6731,6 @@ heap_freeze_prepared_tuples(Buffer buffer, HeapTupleFreeze *tuples, int ntuples)
htup = (HeapTupleHeader) PageGetItem(page, itemid);
heap_execute_freeze_tuple(htup, frz);
}
-
- MarkBufferDirty(buffer);
}
/*
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index 8914d4bf5c8..db8a182a197 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -249,9 +249,8 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
bool do_freeze;
bool all_visible_except_removable;
bool do_prune;
- bool whole_page_freezable;
+ bool do_hint;
bool hint_bit_fpi;
- bool prune_fpi = false;
int64 fpi_before = pgWalUsage.wal_fpi;
/*
@@ -464,10 +463,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
/*
* If checksums are enabled, heap_prune_satisfies_vacuum() may have caused
- * an FPI to be emitted. Then reset fpi_before for no prune case.
+ * an FPI to be emitted.
*/
hint_bit_fpi = fpi_before != pgWalUsage.wal_fpi;
- fpi_before = pgWalUsage.wal_fpi;
/*
* For vacuum, if the whole page will become frozen, we consider
@@ -517,16 +515,16 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
prstate.ndead > 0 ||
prstate.nunused > 0;
+ /* Record number of newly-set-LP_DEAD items for caller */
+ presult->nnewlpdead = prstate.ndead;
+
/*
- * Only incur overhead of checking if we will do an FPI if we might use
- * the information.
+ * Even if we don't prune anything, if we found a new value for the
+ * pd_prune_xid field or the page was marked full, we will update the hint
+ * bit.
*/
- if (do_prune && pagefrz)
- prune_fpi = XLogCheckBufferNeedsBackup(buffer);
-
- /* Is the whole page freezable? And is there something to freeze */
- whole_page_freezable = all_visible_except_removable &&
- presult->all_frozen;
+ do_hint = ((PageHeader) page)->pd_prune_xid != prstate.new_prune_xid ||
+ PageIsFull(page);
/*
* Freeze the page when heap_prepare_freeze_tuple indicates that at least
@@ -539,46 +537,57 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* opportunistic freeze heuristic must be improved; however, for now, try
* to approximate it.
*/
- do_freeze = pagefrz &&
- (pagefrz->freeze_required ||
- (whole_page_freezable && presult->nfrozen > 0 && (prune_fpi || hint_bit_fpi)));
- if (do_freeze)
+ do_freeze = false;
+ if (pagefrz)
{
- heap_pre_freeze_checks(buffer, prstate.frozen, presult->nfrozen);
+ /* Is the whole page freezable? And is there something to freeze? */
+ bool whole_page_freezable = all_visible_except_removable &&
+ presult->all_frozen;
- /*
- * We can use the visibility_cutoff_xid as our cutoff for conflicts
- * when the whole page is eligible to become all-frozen in the VM once
- * we're done with it. Otherwise we generate a conservative cutoff by
- * stepping back from OldestXmin. This avoids false conflicts when
- * hot_standby_feedback is in use.
- */
- if (all_visible_except_removable && presult->all_frozen)
- frz_conflict_horizon = visibility_cutoff_xid;
- else
+ if (pagefrz->freeze_required)
+ do_freeze = true;
+ else if (whole_page_freezable && presult->nfrozen > 0)
{
- /* Avoids false conflicts when hot_standby_feedback in use */
- frz_conflict_horizon = pagefrz->cutoffs->OldestXmin;
- TransactionIdRetreat(frz_conflict_horizon);
+ /*
+ * Freezing would make the page all-frozen. In this case, we will
+ * freeze if we have already emitted an FPI or will do so anyway.
+ * Be sure only to incur the overhead of checking if we will do an
+ * FPI if we may use that information.
+ */
+ if (hint_bit_fpi ||
+ ((do_prune || do_hint) && XLogCheckBufferNeedsBackup(buffer)))
+ {
+ do_freeze = true;
+ }
}
}
- /* Any error while applying the changes is critical */
- START_CRIT_SECTION();
+ /*
+ * Validate the tuples we are considering freezing. We do this even if
+ * pruning and hint bit setting have not emitted an FPI so far because we
+ * still may emit an FPI while setting the page hint bit later. But we
+ * want to avoid doing the pre-freeze checks in a critical section.
+ */
+ if (do_freeze)
+ heap_pre_freeze_checks(buffer, prstate.frozen, presult->nfrozen);
- /* Have we found any prunable items? */
- if (do_prune)
+ if (!do_freeze && (!pagefrz || !presult->all_frozen || presult->nfrozen > 0))
{
/*
- * Apply the planned item changes, then repair page fragmentation, and
- * update the page's hint bit about whether it has free line pointers.
+ * If we will neither freeze tuples on the page nor set the page all
+ * frozen in the visibility map, the page is not all-frozen and there
+ * will be no newly frozen tuples.
*/
- heap_page_prune_execute(buffer, false,
- prstate.redirected, prstate.nredirected,
- prstate.nowdead, prstate.ndead,
- prstate.nowunused, prstate.nunused);
+ presult->all_frozen = false;
+ presult->nfrozen = 0; /* avoid miscounts in instrumentation */
+ }
+
+ /* Any error while applying the changes is critical */
+ START_CRIT_SECTION();
+ if (do_hint)
+ {
/*
* Update the page's pd_prune_xid field to either zero, or the lowest
* XID of any soon-prunable tuple.
@@ -586,12 +595,52 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid;
/*
- * Also clear the "page is full" flag, since there's no point in
- * repeating the prune/defrag process until something else happens to
- * the page.
+ * Clear the "page is full" flag if it is set since there's no point
+ * in repeating the prune/defrag process until something else happens
+ * to the page.
*/
PageClearFull(page);
+ /*
+ * We only needed to update pd_prune_xid and clear the page-is-full
+ * hint bit, this is a non-WAL-logged hint. If we will also freeze or
+ * prune the page, we will mark the buffer dirty below.
+ */
+ if (!do_freeze && !do_prune)
+ MarkBufferDirtyHint(buffer, true);
+ }
+
+ if (do_prune || do_freeze)
+ {
+ /* Apply the planned item changes, then repair page fragmentation. */
+ if (do_prune)
+ {
+ heap_page_prune_execute(buffer, false,
+ prstate.redirected, prstate.nredirected,
+ prstate.nowdead, prstate.ndead,
+ prstate.nowunused, prstate.nunused);
+ }
+
+ if (do_freeze)
+ {
+ /*
+ * We can use the visibility_cutoff_xid as our cutoff for
+ * conflicts when the whole page is eligible to become all-frozen
+ * in the VM once we're done with it. Otherwise we generate a
+ * conservative cutoff by stepping back from OldestXmin. This
+ * avoids false conflicts when hot_standby_feedback is in use.
+ */
+ if (all_visible_except_removable && presult->all_frozen)
+ frz_conflict_horizon = visibility_cutoff_xid;
+ else
+ {
+ /* Avoids false conflicts when hot_standby_feedback in use */
+ frz_conflict_horizon = pagefrz->cutoffs->OldestXmin;
+ TransactionIdRetreat(frz_conflict_horizon);
+ }
+ heap_freeze_prepared_tuples(buffer, prstate.frozen, presult->nfrozen);
+ }
+
MarkBufferDirty(buffer);
/*
@@ -599,72 +648,35 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
*/
if (RelationNeedsWAL(relation))
{
+ /*
+ * The snapshotConflictHorizon for the whole record should be the
+ * most conservative of all the horizons calculated for any of the
+ * possible modifications. If this record will prune tuples, any
+ * transactions on the standby older than the youngest xmax of the
+ * most recently removed tuple this record will prune will
+ * conflict. If this record will freeze tuples, any transactions
+ * on the standby with xids older than the youngest tuple this
+ * record will freeze will conflict.
+ */
+ TransactionId conflict_xid;
+
+ if (TransactionIdFollows(frz_conflict_horizon, prstate.latest_xid_removed))
+ conflict_xid = frz_conflict_horizon;
+ else
+ conflict_xid = prstate.latest_xid_removed;
+
log_heap_prune_and_freeze(relation, buffer,
- prstate.latest_xid_removed,
+ conflict_xid,
true, reason,
- NULL, 0,
+ prstate.frozen, presult->nfrozen,
prstate.redirected, prstate.nredirected,
prstate.nowdead, prstate.ndead,
prstate.nowunused, prstate.nunused);
}
}
- else
- {
- /*
- * If we didn't prune anything, but have found a new value for the
- * pd_prune_xid field, update it and mark the buffer dirty. This is
- * treated as a non-WAL-logged hint.
- *
- * Also clear the "page is full" flag if it is set, since there's no
- * point in repeating the prune/defrag process until something else
- * happens to the page.
- */
- if (((PageHeader) page)->pd_prune_xid != prstate.new_prune_xid ||
- PageIsFull(page))
- {
- ((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid;
- PageClearFull(page);
- MarkBufferDirtyHint(buffer, true);
- }
- }
END_CRIT_SECTION();
- /* Record number of newly-set-LP_DEAD items for caller */
- presult->nnewlpdead = prstate.ndead;
-
- if (do_freeze)
- {
- START_CRIT_SECTION();
-
- Assert(presult->nfrozen > 0);
-
- heap_freeze_prepared_tuples(buffer, prstate.frozen, presult->nfrozen);
-
- MarkBufferDirty(buffer);
-
- /* Now WAL-log freezing if necessary */
- if (RelationNeedsWAL(relation))
- log_heap_prune_and_freeze(relation, buffer,
- frz_conflict_horizon, false, reason,
- prstate.frozen, presult->nfrozen,
- NULL, 0, /* redirected */
- NULL, 0, /* dead */
- NULL, 0); /* unused */
-
- END_CRIT_SECTION();
- }
- else if (!pagefrz || !presult->all_frozen || presult->nfrozen > 0)
- {
- /*
- * If we will neither freeze tuples on the page nor set the page all
- * frozen in the visibility map, the page is not all frozen and there
- * will be no newly frozen tuples.
- */
- presult->all_frozen = false;
- presult->nfrozen = 0; /* avoid miscounts in instrumentation */
- }
-
/*
* For callers planning to update the visibility map, the conflict horizon
* for that record must be the newest xmin on the page. However, if the
@@ -681,9 +693,10 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* tuples on the page, if we will set the page all-frozen in the
* visibility map, we can advance relfrozenxid and relminmxid to the
* values in pagefrz->FreezePageRelfrozenXid and
- * pagefrz->FreezePageRelminMxid.
+ * pagefrz->FreezePageRelminMxid. MFIXME: which one should be pick if
+ * presult->nfrozen == 0 and presult->all_frozen = True.
*/
- if (presult->all_frozen || presult->nfrozen > 0)
+ if (presult->nfrozen > 0)
{
presult->new_relfrozenxid = pagefrz->FreezePageRelfrozenXid;
presult->new_relminmxid = pagefrz->FreezePageRelminMxid;
--
2.40.1
--ck6erxojvlx23byk
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v7-0013-Set-hastup-in-heap_page_prune.patch"
^ permalink raw reply [nested|flat] 18+ messages in thread
* [PATCH v7 12/16] Merge prune and freeze records
@ 2024-03-26 13:37 Melanie Plageman <[email protected]>
0 siblings, 0 replies; 18+ messages in thread
From: Melanie Plageman @ 2024-03-26 13:37 UTC (permalink / raw)
When both pruning and freezing is done, this means a single, combined
WAL record is emitted for both operations. This will reduce the number
of WAL records emitted.
When there are only tuples to freeze present, we can avoid taking a full
cleanup lock when replaying the record.
---
src/backend/access/heap/heapam.c | 2 -
src/backend/access/heap/pruneheap.c | 215 +++++++++++++++-------------
2 files changed, 114 insertions(+), 103 deletions(-)
diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 1c1785994b1..5d8f183085d 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -6731,8 +6731,6 @@ heap_freeze_prepared_tuples(Buffer buffer, HeapTupleFreeze *tuples, int ntuples)
htup = (HeapTupleHeader) PageGetItem(page, itemid);
heap_execute_freeze_tuple(htup, frz);
}
-
- MarkBufferDirty(buffer);
}
/*
diff --git a/src/backend/access/heap/pruneheap.c b/src/backend/access/heap/pruneheap.c
index 8914d4bf5c8..db8a182a197 100644
--- a/src/backend/access/heap/pruneheap.c
+++ b/src/backend/access/heap/pruneheap.c
@@ -249,9 +249,8 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
bool do_freeze;
bool all_visible_except_removable;
bool do_prune;
- bool whole_page_freezable;
+ bool do_hint;
bool hint_bit_fpi;
- bool prune_fpi = false;
int64 fpi_before = pgWalUsage.wal_fpi;
/*
@@ -464,10 +463,9 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
/*
* If checksums are enabled, heap_prune_satisfies_vacuum() may have caused
- * an FPI to be emitted. Then reset fpi_before for no prune case.
+ * an FPI to be emitted.
*/
hint_bit_fpi = fpi_before != pgWalUsage.wal_fpi;
- fpi_before = pgWalUsage.wal_fpi;
/*
* For vacuum, if the whole page will become frozen, we consider
@@ -517,16 +515,16 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
prstate.ndead > 0 ||
prstate.nunused > 0;
+ /* Record number of newly-set-LP_DEAD items for caller */
+ presult->nnewlpdead = prstate.ndead;
+
/*
- * Only incur overhead of checking if we will do an FPI if we might use
- * the information.
+ * Even if we don't prune anything, if we found a new value for the
+ * pd_prune_xid field or the page was marked full, we will update the hint
+ * bit.
*/
- if (do_prune && pagefrz)
- prune_fpi = XLogCheckBufferNeedsBackup(buffer);
-
- /* Is the whole page freezable? And is there something to freeze */
- whole_page_freezable = all_visible_except_removable &&
- presult->all_frozen;
+ do_hint = ((PageHeader) page)->pd_prune_xid != prstate.new_prune_xid ||
+ PageIsFull(page);
/*
* Freeze the page when heap_prepare_freeze_tuple indicates that at least
@@ -539,46 +537,57 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* opportunistic freeze heuristic must be improved; however, for now, try
* to approximate it.
*/
- do_freeze = pagefrz &&
- (pagefrz->freeze_required ||
- (whole_page_freezable && presult->nfrozen > 0 && (prune_fpi || hint_bit_fpi)));
- if (do_freeze)
+ do_freeze = false;
+ if (pagefrz)
{
- heap_pre_freeze_checks(buffer, prstate.frozen, presult->nfrozen);
+ /* Is the whole page freezable? And is there something to freeze? */
+ bool whole_page_freezable = all_visible_except_removable &&
+ presult->all_frozen;
- /*
- * We can use the visibility_cutoff_xid as our cutoff for conflicts
- * when the whole page is eligible to become all-frozen in the VM once
- * we're done with it. Otherwise we generate a conservative cutoff by
- * stepping back from OldestXmin. This avoids false conflicts when
- * hot_standby_feedback is in use.
- */
- if (all_visible_except_removable && presult->all_frozen)
- frz_conflict_horizon = visibility_cutoff_xid;
- else
+ if (pagefrz->freeze_required)
+ do_freeze = true;
+ else if (whole_page_freezable && presult->nfrozen > 0)
{
- /* Avoids false conflicts when hot_standby_feedback in use */
- frz_conflict_horizon = pagefrz->cutoffs->OldestXmin;
- TransactionIdRetreat(frz_conflict_horizon);
+ /*
+ * Freezing would make the page all-frozen. In this case, we will
+ * freeze if we have already emitted an FPI or will do so anyway.
+ * Be sure only to incur the overhead of checking if we will do an
+ * FPI if we may use that information.
+ */
+ if (hint_bit_fpi ||
+ ((do_prune || do_hint) && XLogCheckBufferNeedsBackup(buffer)))
+ {
+ do_freeze = true;
+ }
}
}
- /* Any error while applying the changes is critical */
- START_CRIT_SECTION();
+ /*
+ * Validate the tuples we are considering freezing. We do this even if
+ * pruning and hint bit setting have not emitted an FPI so far because we
+ * still may emit an FPI while setting the page hint bit later. But we
+ * want to avoid doing the pre-freeze checks in a critical section.
+ */
+ if (do_freeze)
+ heap_pre_freeze_checks(buffer, prstate.frozen, presult->nfrozen);
- /* Have we found any prunable items? */
- if (do_prune)
+ if (!do_freeze && (!pagefrz || !presult->all_frozen || presult->nfrozen > 0))
{
/*
- * Apply the planned item changes, then repair page fragmentation, and
- * update the page's hint bit about whether it has free line pointers.
+ * If we will neither freeze tuples on the page nor set the page all
+ * frozen in the visibility map, the page is not all-frozen and there
+ * will be no newly frozen tuples.
*/
- heap_page_prune_execute(buffer, false,
- prstate.redirected, prstate.nredirected,
- prstate.nowdead, prstate.ndead,
- prstate.nowunused, prstate.nunused);
+ presult->all_frozen = false;
+ presult->nfrozen = 0; /* avoid miscounts in instrumentation */
+ }
+
+ /* Any error while applying the changes is critical */
+ START_CRIT_SECTION();
+ if (do_hint)
+ {
/*
* Update the page's pd_prune_xid field to either zero, or the lowest
* XID of any soon-prunable tuple.
@@ -586,12 +595,52 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid;
/*
- * Also clear the "page is full" flag, since there's no point in
- * repeating the prune/defrag process until something else happens to
- * the page.
+ * Clear the "page is full" flag if it is set since there's no point
+ * in repeating the prune/defrag process until something else happens
+ * to the page.
*/
PageClearFull(page);
+ /*
+ * We only needed to update pd_prune_xid and clear the page-is-full
+ * hint bit, this is a non-WAL-logged hint. If we will also freeze or
+ * prune the page, we will mark the buffer dirty below.
+ */
+ if (!do_freeze && !do_prune)
+ MarkBufferDirtyHint(buffer, true);
+ }
+
+ if (do_prune || do_freeze)
+ {
+ /* Apply the planned item changes, then repair page fragmentation. */
+ if (do_prune)
+ {
+ heap_page_prune_execute(buffer, false,
+ prstate.redirected, prstate.nredirected,
+ prstate.nowdead, prstate.ndead,
+ prstate.nowunused, prstate.nunused);
+ }
+
+ if (do_freeze)
+ {
+ /*
+ * We can use the visibility_cutoff_xid as our cutoff for
+ * conflicts when the whole page is eligible to become all-frozen
+ * in the VM once we're done with it. Otherwise we generate a
+ * conservative cutoff by stepping back from OldestXmin. This
+ * avoids false conflicts when hot_standby_feedback is in use.
+ */
+ if (all_visible_except_removable && presult->all_frozen)
+ frz_conflict_horizon = visibility_cutoff_xid;
+ else
+ {
+ /* Avoids false conflicts when hot_standby_feedback in use */
+ frz_conflict_horizon = pagefrz->cutoffs->OldestXmin;
+ TransactionIdRetreat(frz_conflict_horizon);
+ }
+ heap_freeze_prepared_tuples(buffer, prstate.frozen, presult->nfrozen);
+ }
+
MarkBufferDirty(buffer);
/*
@@ -599,72 +648,35 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
*/
if (RelationNeedsWAL(relation))
{
+ /*
+ * The snapshotConflictHorizon for the whole record should be the
+ * most conservative of all the horizons calculated for any of the
+ * possible modifications. If this record will prune tuples, any
+ * transactions on the standby older than the youngest xmax of the
+ * most recently removed tuple this record will prune will
+ * conflict. If this record will freeze tuples, any transactions
+ * on the standby with xids older than the youngest tuple this
+ * record will freeze will conflict.
+ */
+ TransactionId conflict_xid;
+
+ if (TransactionIdFollows(frz_conflict_horizon, prstate.latest_xid_removed))
+ conflict_xid = frz_conflict_horizon;
+ else
+ conflict_xid = prstate.latest_xid_removed;
+
log_heap_prune_and_freeze(relation, buffer,
- prstate.latest_xid_removed,
+ conflict_xid,
true, reason,
- NULL, 0,
+ prstate.frozen, presult->nfrozen,
prstate.redirected, prstate.nredirected,
prstate.nowdead, prstate.ndead,
prstate.nowunused, prstate.nunused);
}
}
- else
- {
- /*
- * If we didn't prune anything, but have found a new value for the
- * pd_prune_xid field, update it and mark the buffer dirty. This is
- * treated as a non-WAL-logged hint.
- *
- * Also clear the "page is full" flag if it is set, since there's no
- * point in repeating the prune/defrag process until something else
- * happens to the page.
- */
- if (((PageHeader) page)->pd_prune_xid != prstate.new_prune_xid ||
- PageIsFull(page))
- {
- ((PageHeader) page)->pd_prune_xid = prstate.new_prune_xid;
- PageClearFull(page);
- MarkBufferDirtyHint(buffer, true);
- }
- }
END_CRIT_SECTION();
- /* Record number of newly-set-LP_DEAD items for caller */
- presult->nnewlpdead = prstate.ndead;
-
- if (do_freeze)
- {
- START_CRIT_SECTION();
-
- Assert(presult->nfrozen > 0);
-
- heap_freeze_prepared_tuples(buffer, prstate.frozen, presult->nfrozen);
-
- MarkBufferDirty(buffer);
-
- /* Now WAL-log freezing if necessary */
- if (RelationNeedsWAL(relation))
- log_heap_prune_and_freeze(relation, buffer,
- frz_conflict_horizon, false, reason,
- prstate.frozen, presult->nfrozen,
- NULL, 0, /* redirected */
- NULL, 0, /* dead */
- NULL, 0); /* unused */
-
- END_CRIT_SECTION();
- }
- else if (!pagefrz || !presult->all_frozen || presult->nfrozen > 0)
- {
- /*
- * If we will neither freeze tuples on the page nor set the page all
- * frozen in the visibility map, the page is not all frozen and there
- * will be no newly frozen tuples.
- */
- presult->all_frozen = false;
- presult->nfrozen = 0; /* avoid miscounts in instrumentation */
- }
-
/*
* For callers planning to update the visibility map, the conflict horizon
* for that record must be the newest xmin on the page. However, if the
@@ -681,9 +693,10 @@ heap_page_prune_and_freeze(Relation relation, Buffer buffer,
* tuples on the page, if we will set the page all-frozen in the
* visibility map, we can advance relfrozenxid and relminmxid to the
* values in pagefrz->FreezePageRelfrozenXid and
- * pagefrz->FreezePageRelminMxid.
+ * pagefrz->FreezePageRelminMxid. MFIXME: which one should be pick if
+ * presult->nfrozen == 0 and presult->all_frozen = True.
*/
- if (presult->all_frozen || presult->nfrozen > 0)
+ if (presult->nfrozen > 0)
{
presult->new_relfrozenxid = pagefrz->FreezePageRelfrozenXid;
presult->new_relminmxid = pagefrz->FreezePageRelminMxid;
--
2.40.1
--ck6erxojvlx23byk
Content-Type: text/x-diff; charset=us-ascii
Content-Disposition: attachment;
filename="v7-0013-Set-hastup-in-heap_page_prune.patch"
^ permalink raw reply [nested|flat] 18+ messages in thread
* Re: BF mamba failure
@ 2024-10-17 04:24 Michael Paquier <[email protected]>
2024-11-14 07:55 ` Re: BF mamba failure Michael Paquier <[email protected]>
0 siblings, 1 reply; 18+ messages in thread
From: Michael Paquier @ 2024-10-17 04:24 UTC (permalink / raw)
To: Bertrand Drouvot <[email protected]>; +Cc: Kouber Saparev <[email protected]>; [email protected]
On Wed, Oct 16, 2024 at 10:11:08AM +0000, Bertrand Drouvot wrote:
> Indeed, in pgstat_release_entry_ref(), we're doing:
>
> if (pg_atomic_fetch_sub_u32(&entry_ref->shared_entry->refcount, 1) == 1)
> .
> .
> shent = dshash_find(pgStatLocal.shared_hash,
> &entry_ref->shared_entry->key,
> true);
>
> I wonder if we are not decrementing &entry_ref->shared_entry->refcount too early.
>
> I mean, wouldn't that make sense to decrement it after the dshash_find() call?
> (to ensure a "proper" whole entry locking, done in dshash_find(), first)
Making that a two-step process (first step to read the refcount,
second step to decrement it after taking the exclusive lock through
dshash_find) would make the logic more complicated what what we have
now, without offering more protection, afaik, because you'd still need
to worry about a race condition between the first and second steps.
Making this a one-step only would incur more dshash_find() calls than
we actually need, and I would not underestimate that under a
heavily-concurrent pgstat_release_entry_ref() path taken.
> Yeah, FWIW, we would be going from 32 bytes:
> /* total size (bytes): 32 */
>
> to 40 bytes (with the patch applied):
> /* total size (bytes): 40 */
>
> Due to the padding, that's a 8 bytes increase while we're adding "only" 4 bytes.
I have spent some time digging into all the original pgstat threads
dealing with the shmem implementation or dshash, and I'm not really
seeing anybody stressing on the size of the individual hash entries.
This stuff was already wasting space with padding originally, so
perhaps we're stressing too much here? Would anybody like to comment?
--
Michael
Attachments:
[application/pgp-signature] signature.asc (833B, ../../[email protected]/2-signature.asc)
download
^ permalink raw reply [nested|flat] 18+ messages in thread
* Re: BF mamba failure
2024-10-17 04:24 Re: BF mamba failure Michael Paquier <[email protected]>
@ 2024-11-14 07:55 ` Michael Paquier <[email protected]>
2024-11-14 10:07 ` Re: BF mamba failure Bertrand Drouvot <[email protected]>
0 siblings, 1 reply; 18+ messages in thread
From: Michael Paquier @ 2024-11-14 07:55 UTC (permalink / raw)
To: Bertrand Drouvot <[email protected]>; +Cc: Kouber Saparev <[email protected]>; [email protected]
On Thu, Oct 17, 2024 at 01:24:50PM +0900, Michael Paquier wrote:
>> Yeah, FWIW, we would be going from 32 bytes:
>> /* total size (bytes): 32 */
>>
>> to 40 bytes (with the patch applied):
>> /* total size (bytes): 40 */
>>
>> Due to the padding, that's a 8 bytes increase while we're adding "only" 4 bytes.
>
> I have spent some time digging into all the original pgstat threads
> dealing with the shmem implementation or dshash, and I'm not really
> seeing anybody stressing on the size of the individual hash entries.
> This stuff was already wasting space with padding originally, so
> perhaps we're stressing too much here? Would anybody like to comment?
I've been going through this patch again, and the failures that could
be seen because of such failures, like standbys failing in an
unpredictible way is not cool, so I am planning to apply the attached
down to 15 now that the release has colled down. At the end I am not
really stressing about this addition in the structure for the sake of
making the stats entries safe to handle.
I did not like much the name "agecount" though, used to cross-check
how many times an entry is reused in shared memory and in the local
copy we keep in a process, so I've renamed it to "generation".
--
Michael
Attachments:
[text/x-diff] v2-0001-Introduce-generation-counter-for-pgstats-entries.patch (5.0K, ../../[email protected]/2-v2-0001-Introduce-generation-counter-for-pgstats-entries.patch)
download | inline diff:
From abd8b567f3cd97ca4e0282ce7657f64807f8c008 Mon Sep 17 00:00:00 2001
From: Michael Paquier <[email protected]>
Date: Thu, 14 Nov 2024 16:53:58 +0900
Subject: [PATCH v2] Introduce "generation" counter for pgstats entries
This fixes a set of race conditions with cumulative statistics where a
shared stats entry could be dropped while it should still be valid
when it gets reused. This can happen for the following case, causing
the same hash key to be used:
- replication slots that compute internally an index number.
- other object types, with a wraparound involved.
- As of PostgreSQL 18, custom pgstats kinds.
The "generation" is tracked in the shared entries, initialized at 0 when
an entry is created and incremented when the same entry is reused, to
avoid concurrent turbulences on drop because of other backends still
holding a reference to it.
---
src/include/utils/pgstat_internal.h | 14 ++++++++
src/backend/utils/activity/pgstat_shmem.c | 40 ++++++++++++++++++++---
2 files changed, 49 insertions(+), 5 deletions(-)
diff --git a/src/include/utils/pgstat_internal.h b/src/include/utils/pgstat_internal.h
index 61b2e1f96b..45f5901d45 100644
--- a/src/include/utils/pgstat_internal.h
+++ b/src/include/utils/pgstat_internal.h
@@ -94,6 +94,14 @@ typedef struct PgStatShared_HashEntry
*/
pg_atomic_uint32 refcount;
+ /*
+ * Counter tracking the number of times the entry has been reused.
+ *
+ * Set to 0 when the entry is created, and incremented by one each time
+ * the shared entry is reinitialized with pgstat_reinit_entry().
+ */
+ pg_atomic_uint32 generation;
+
/*
* Pointer to shared stats. The stats entry always starts with
* PgStatShared_Common, embedded in a larger struct containing the
@@ -133,6 +141,12 @@ typedef struct PgStat_EntryRef
*/
PgStatShared_Common *shared_stats;
+ /*
+ * Copy of PgStatShared_HashEntry->generation, keeping locally track of
+ * the shared stats entry "generation" retrieved (number of times reused).
+ */
+ uint32 generation;
+
/*
* Pending statistics data that will need to be flushed to shared memory
* stats eventually. Each stats kind utilizing pending data defines what
diff --git a/src/backend/utils/activity/pgstat_shmem.c b/src/backend/utils/activity/pgstat_shmem.c
index c1b7ff76b1..c8ee0bd0b0 100644
--- a/src/backend/utils/activity/pgstat_shmem.c
+++ b/src/backend/utils/activity/pgstat_shmem.c
@@ -304,6 +304,11 @@ pgstat_init_entry(PgStat_Kind kind,
* further if a longer lived reference is needed.
*/
pg_atomic_init_u32(&shhashent->refcount, 1);
+
+ /*
+ * Initialize generation to 0, as freshly initialized.
+ */
+ pg_atomic_init_u32(&shhashent->generation, 0);
shhashent->dropped = false;
chunk = dsa_allocate0(pgStatLocal.dsa, pgstat_get_kind_info(kind)->shared_size);
@@ -327,6 +332,12 @@ pgstat_reinit_entry(PgStat_Kind kind, PgStatShared_HashEntry *shhashent)
/* mark as not dropped anymore */
pg_atomic_fetch_add_u32(&shhashent->refcount, 1);
+
+ /*
+ * Increment generation, to let any backend with local references know
+ * that what they point to is outdated.
+ */
+ pg_atomic_fetch_add_u32(&shhashent->generation, 1);
shhashent->dropped = false;
/* reinitialize content */
@@ -367,6 +378,7 @@ pgstat_acquire_entry_ref(PgStat_EntryRef *entry_ref,
entry_ref->shared_stats = shheader;
entry_ref->shared_entry = shhashent;
+ entry_ref->generation = pg_atomic_read_u32(&shhashent->generation);
}
/*
@@ -532,7 +544,8 @@ pgstat_get_entry_ref(PgStat_Kind kind, Oid dboid, uint64 objid, bool create,
* case are replication slot stats, where a new slot can be
* created with the same index just after dropping. But oid
* wraparound can lead to other cases as well. We just reset the
- * stats to their plain state.
+ * stats to their plain state, while incrementing its "generation"
+ * in the shared entry for any remaining local references.
*/
shheader = pgstat_reinit_entry(kind, shhashent);
pgstat_acquire_entry_ref(entry_ref, shhashent, shheader);
@@ -599,10 +612,27 @@ pgstat_release_entry_ref(PgStat_HashKey key, PgStat_EntryRef *entry_ref,
if (!shent)
elog(ERROR, "could not find just referenced shared stats entry");
- Assert(pg_atomic_read_u32(&entry_ref->shared_entry->refcount) == 0);
- Assert(entry_ref->shared_entry == shent);
-
- pgstat_free_entry(shent, NULL);
+ /*
+ * This entry may have been reinitialized while trying to release
+ * it, so double-check that it has not been reused while holding a
+ * lock on its shared entry.
+ */
+ if (pg_atomic_read_u32(&entry_ref->shared_entry->generation) ==
+ entry_ref->generation)
+ {
+ /* Same generation, so we're OK with the removal */
+ Assert(pg_atomic_read_u32(&entry_ref->shared_entry->refcount) == 0);
+ Assert(entry_ref->shared_entry == shent);
+ pgstat_free_entry(shent, NULL);
+ }
+ else
+ {
+ /*
+ * Shared stats entry has been reinitialized, so do not drop
+ * its shared entry, only release its lock.
+ */
+ dshash_release_lock(pgStatLocal.shared_hash, shent);
+ }
}
}
--
2.45.2
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^ permalink raw reply [nested|flat] 18+ messages in thread
* Re: BF mamba failure
2024-10-17 04:24 Re: BF mamba failure Michael Paquier <[email protected]>
2024-11-14 07:55 ` Re: BF mamba failure Michael Paquier <[email protected]>
@ 2024-11-14 10:07 ` Bertrand Drouvot <[email protected]>
0 siblings, 0 replies; 18+ messages in thread
From: Bertrand Drouvot @ 2024-11-14 10:07 UTC (permalink / raw)
To: Michael Paquier <[email protected]>; +Cc: Kouber Saparev <[email protected]>; [email protected]
Hi,
On Thu, Nov 14, 2024 at 04:55:23PM +0900, Michael Paquier wrote:
> I've been going through this patch again, and the failures that could
> be seen because of such failures, like standbys failing in an
> unpredictible way is not cool, so I am planning to apply the attached
> down to 15 now that the release has colled down. At the end I am not
> really stressing about this addition in the structure for the sake of
> making the stats entries safe to handle.
I don't think the addition is a concern too.
> I did not like much the name "agecount" though, used to cross-check
> how many times an entry is reused in shared memory and in the local
> copy we keep in a process, so I've renamed it to "generation".
"generation" sounds more appropriate to me too.
The approach to avoid the error sounds reasonable to me.
Just 2 comments about the patch:
=== 1
Maybe use "generation" instead of generation in the comments (where it's not done,
some comments do it already).
=== 2
We could think about adding a test. That should be doable with replication slots
or custom pgstats kinds and probably injection points. But I'm not sure that's
worth it, as the code in the patch looks "simple" enough. Thoughts?
Regards,
--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com
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-- links below jump to the message on this page --
2018-06-22 03:45 Incorrect comments in commit_ts.c shao bret <[email protected]>
2018-06-22 04:31 ` Michael Paquier <[email protected]>
2018-06-22 07:34 ` =?gb2312?B?tPC4tDogSW5jb3JyZWN0IGNvbW1lbnRzIGluIGNvbW1pdF90cy5j?= shao bret <[email protected]>
2024-01-07 22:55 [PATCH v3 12/17] Merge prune and freeze records Melanie Plageman <[email protected]>
2024-01-07 22:55 [PATCH v4 13/19] Merge prune and freeze records Melanie Plageman <[email protected]>
2024-01-07 22:55 [PATCH v4 13/19] Merge prune and freeze records Melanie Plageman <[email protected]>
2024-01-07 22:55 [PATCH v4 13/19] Merge prune and freeze records Melanie Plageman <[email protected]>
2024-01-07 22:55 [PATCH v2 12/17] Merge prune and freeze records Melanie Plageman <[email protected]>
2024-01-07 22:55 [PATCH v3 12/17] Merge prune and freeze records Melanie Plageman <[email protected]>
2024-01-07 22:55 [PATCH v3 12/17] Merge prune and freeze records Melanie Plageman <[email protected]>
2024-01-07 22:55 [PATCH v2 12/17] Merge prune and freeze records Melanie Plageman <[email protected]>
2024-01-07 22:55 [PATCH v2 12/17] Merge prune and freeze records Melanie Plageman <[email protected]>
2024-03-26 13:37 [PATCH v9 12/21] Merge prune and freeze records Melanie Plageman <[email protected]>
2024-03-26 13:37 [PATCH v7 12/16] Merge prune and freeze records Melanie Plageman <[email protected]>
2024-03-26 13:37 [PATCH v7 12/16] Merge prune and freeze records Melanie Plageman <[email protected]>
2024-10-17 04:24 Re: BF mamba failure Michael Paquier <[email protected]>
2024-11-14 07:55 ` Re: BF mamba failure Michael Paquier <[email protected]>
2024-11-14 10:07 ` Re: BF mamba failure Bertrand Drouvot <[email protected]>
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